gcc 4 only: modified the previous change to allow fallback to local C++ system headers

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@18866 a95241bf-73f2-0310-859d-f6bbb57e9c96

configure

@@ -110,18 +110,21 @@ standard_gcc_settings()
 			haikuSharedLibStdCxx=`$HAIKU_CC -print-file-name=libstdc++.so`
 			haikuStaticLibSupCxx=`$HAIKU_CC -print-file-name=libsupc++.a`
 			haikuSharedLibSupCxx=`$HAIKU_CC -print-file-name=libsupc++.so`
-			# only when building a cross compiler use the local (non haiku) C++ headers
-			if [ -n "$buildCrossTools"  ]; then
-				local headers=$gccdir/../../../../include/c++/$haikuGCCVersion
-				haikuCxxHeadersDir=$headers
-				for d in $haikuGCCMachine backward ext; do
-					# Note: We need the line break, otherwise the line might become
-					# too long for jam (512 bytes max).
-					haikuCxxHeadersDir="$haikuCxxHeadersDir
-						$headers/$d"
-				done
+			local headers=$gccdir/../../../../include/c++/$haikuGCCVersion
+			haikuCxxHeadersDir=$headers
+			for d in $haikuGCCMachine backward ext; do
+				# Note: We need the line break, otherwise the line might become
+				# too long for jam (512 bytes max).
+				haikuCxxHeadersDir="$haikuCxxHeadersDir
+					$headers/$d"
+			done
+
+			if [ "$buildCrossTools" = "" ]; then
+				# when not building the crosscompiler, we use cpp headers from 
+				# tree first, but fallback to local C++ system headers (like <new>)
+				haikuCxxHeadersDir="headers/cpp $haikuCxxHeadersDir"
 			fi
-			
+
 			if [ $haikuStaticLibStdCxx = libstdc++.a ]; then
 				haikuStaticLibStdCxx=
 			fi