configure: Rewrite implementation of --update.

Previously --update was kind of a hack, as it just dumped all
the variables from BuildConfig back into ./configure and attempted
to rerun from there.

Instead, now we store all of the variables and environs configure
was invoked with in the top of BuildConfig and re-call it using them.
This is much more robust, as configure will actually recompute
all of the values from the BuildConfig.

As a side effect, if configure was originally invoked to build crosstools,
it would have done so again, so instead add a check to see if they
exist, and skip them if they do. It's easy enough to delete the
directory if you want to force a crosstools rebuild.

Briefly discussed with mmlr on IRC.

build/scripts/convert_build_config_to_shell_format.pl

@@ -1,23 +0,0 @@
-#!/usr/bin/perl
-
-use warnings;
-use strict;
-
-=head1 convert_build_config_to_shell_format
-
-This simple script converts its standard input from the jam-specific format
-that is being used in BuildSetup into a format that's understood by sh.
-
-=cut
-
-my $data;
-while (my $line = <>) {
-	$data .= $line;
-	if ($data =~ m{\s*([+\w]+)\s*\?=\s*\"?([^;]*?)\"?\s*;}gms) {
-		my ($variable, $value) = ($1, $2);
-		$variable =~ tr{+}{X};	# '+' is illegal as part of shell variable
-		print "$variable='$value'\n";
-		$data = '';
-	}
-}
-

configure

@@ -12,6 +12,9 @@ usage()
 
 Usage: $0 <options>
 options:
+  --help                      Prints out this help.
+  --update                    Re-runs last configure invocation [must be given
+                              as first option!]
   --bootstrap <haikuporter> <HaikuPorts cross repo> <HaikuPorts repo>
                               Prepare for a bootstrap build. No pre-built
                               packages will be used, instead they will be built
@@ -51,7 +54,6 @@ options:
                               official -- the official Haiku distribution.
                               compatible -- a Haiku Compatible (tm) distro.
                               default -- any other distro (default value).
-  --help                      Prints out this help.
   --host-only                 Configure for building tools for the build host
                               only. Haiku cannot be built when configured like
                               this.
@@ -59,7 +61,7 @@ options:
                               ideas and techniques. If this option is not
                               specified, the resulting distribution may still
                               implement patented ideas and techniques. This
-                              option only disables code that is currently known
+                              option only enables code that is currently known
                               to be problematic.
   --include-sources           Includes the source code of projects that require
                               either an offer of source code or a copy of the
@@ -81,8 +83,6 @@ options:
                               first occurrence specifies the primary
                               architecture of the Haiku to build, subsequent
                               ones the secondary architectures.
-  --update                    re-runs last configure invocation [must be given
-                              as first option!]
   --use-clang <arch>          Build with host Clang instead of GCC cross
                               compiler, targeting <arch>
   --use-gcc-pipe              Build with GCC option -pipe. Speeds up the build
@@ -415,6 +415,17 @@ cd "$currentDir"
 
 # backup the passed arguments
 configureArgs="$@"
+configurePath=$0
+
+# backup relevant environs
+configureEnvirons=
+for var in `env`; do
+	case "$var" in
+		CC\=*|HAIKU*\=*)
+			configureEnvirons="$configureEnvirons $var"
+			;;
+	esac
+done
 
 # internal default parameter values
 #
@@ -502,17 +513,20 @@ if [ "$1" = "--update" ]; then
 		echo $0 --update: \'$buildConfigFile\' not found - updating not possible.
 		exit 1
 	fi
-	if ! type perl >/dev/null 2>&1; then
+	# get last configure invocation and flags from BuildConfig and call ourselves with it
-		echo $0 --update: \'perl\' not found - updating not possible.
+	lastPwd=`grep "#d " "$buildConfigFile" | cut -c 4-`
+	lastConfig=`grep "#c " "$buildConfigFile" | cut -c 4-`
+	lastEnv=`grep "#e " "$buildConfigFile" | cut -c 4-`
+	lastArgs=`grep "#a " "$buildConfigFile" | cut -c 4-`
+	if [ -z "$lastConfig" ]; then
+		echo "$0 --update: The previous configure invocation was not properly" \
+			"encoded into '$buildConfigFile' - updating not possible."
 		exit 1
 	fi
-	# convert BuildConfig from jam format to shell format and evaluate it
+	cd $lastPwd
-	shellConfigFile="${buildConfigFile}.shell"
+	export $lastEnv
-	perl "$sourceDir/build/scripts/convert_build_config_to_shell_format.pl" \
+	$lastConfig $lastArgs
-		<"$buildConfigFile" >"$shellConfigFile"
+	exit $?
-	. "$shellConfigFile"
-	rm "$shellConfigFile"
-	shift
 fi
 
 # parse parameters
@@ -791,6 +805,7 @@ else
 				*)					MAKE=make;;
 			esac
 
+			if [ ! -d "$crossToolsDir" ]; then
 				MAKE=$MAKE \
 				SECONDARY_ARCH=$secondaryArch \
 				HAIKU_USE_GCC_GRAPHITE=`get_variable \
@@ -799,6 +814,9 @@ else
 				HAIKU_USE_GDB="$gdbSources" \
 				"$script" $scriptArgs "$sourceDir" "$buildCrossTools" \
 					"$crossToolsDir" $buildCrossToolsJobs || exit 1
+			else
+				echo "$targetArch crosstools already exist in $crossToolsDir; skipping build"
+			fi
 			crossToolsPrefix="$crossToolsDir/bin/${targetMachine}-"
 		fi
 
@@ -863,10 +881,14 @@ fi
 
 # Generate BuildConfig
 cat << EOF > "$buildConfigFile"
-# BuildConfig
+# -- WARNING --
-# Note: This file has been automatically generated by configure with the
+# This file was AUTOMATICALLY GENERATED by configure, and will be completely
-# following arguments:
+# overwritten the next time configure is run.
-# ${configureArgs}
+#
+#d ${currentDir}
+#c ${configurePath}
+#e ${configureEnvirons}
+#a ${configureArgs}
 
 TARGET_PLATFORM 			?= "${TARGET_PLATFORM}" ;
 HOST_PLATFORM				?= "${HOST_PLATFORM}" ;