Re-enable quoting in fltk-config(.in) [fix PR #17]

- add some more missing quotes
- use `eval` to execute the compile/build command.

Tested with both configure/Make and CMake (Ninja) after installing
in a path that contains spaces (Linux only so far).

fltk-config.in

@@ -44,12 +44,12 @@ CAIROFLAGS="@CAIROFLAGS@"
 # otherwise it is an empty string
 BINARY_DIR=@BINARY_DIR@
 
-prefix=@prefix@
+prefix="@prefix@"
-exec_prefix=@exec_prefix@
+exec_prefix="@exec_prefix@"
 exec_prefix_set=no
-includedir=@includedir@
+includedir="@includedir@"
-libdir=@libdir@
+libdir="@libdir@"
-srcdir=@srcdir@
+srcdir="@srcdir@"
 
 # BEGIN fltk-config code
 
@@ -72,25 +72,25 @@ GLLIBS="@GLLIBS@"
 
 # Check bundled image libraries in source tree
 if test -f "$libdir/libfltk_jpeg.a"; then
-    CFLAGS="-I$includedir/jpeg $CFLAGS"
+    CFLAGS="-I'$includedir/jpeg' $CFLAGS"
-    CXXFLAGS="-I$includedir/jpeg $CXXFLAGS"
+    CXXFLAGS="-I'$includedir/jpeg' $CXXFLAGS"
 fi
 
 if test -f "$libdir/libfltk_z.a"; then
-    CFLAGS="-I$includedir/zlib $CFLAGS"
+    CFLAGS="-I'$includedir/zlib' $CFLAGS"
-    CXXFLAGS="-I$includedir/zlib $CXXFLAGS"
+    CXXFLAGS="-I'$includedir/zlib' $CXXFLAGS"
 fi
 
 if test -f "$libdir/libfltk_png.a"; then
-    CFLAGS="-I$includedir/png $CFLAGS"
+    CFLAGS="-I'$includedir/png' $CFLAGS"
-    CXXFLAGS="-I$includedir/png $CXXFLAGS"
+    CXXFLAGS="-I'$includedir/png' $CXXFLAGS"
 fi
 
 # Check bundled image libraries in installation folder.
 # Note: jpeg, png, and zlib headers are installed in FL/images
-if test -d $includedir/FL/images; then
+if test -d "$includedir/FL/images"; then
-    CFLAGS="-I$includedir/FL/images $CFLAGS"
+    CFLAGS="-I'$includedir/FL/images' $CFLAGS"
-    CXXFLAGS="-I$includedir/FL/images $CXXFLAGS"
+    CXXFLAGS="-I'$includedir/FL/images' $CXXFLAGS"
 fi
 
 # Cairo support
@@ -254,39 +254,39 @@ do
 done
 
 if test "$includedir" != /usr/include; then
-    includes="-I$includedir"
+    includes="-I'$includedir'"
 else
     includes=
 fi
 
 # prepend build directory for fltk-config in CMake build folder
 if test -n "$BINARY_DIR"; then
-    includes="-I$BINARY_DIR $includes"
+    includes="-I'$BINARY_DIR' $includes"
 fi
 
 if test "$libdir" != /usr/lib -a "$libdir" != /usr/lib32; then
-    libs="-L$libdir"
+    libs="-L'$libdir'"
 else
     libs=
 fi
 
 # Calculate needed libraries
-LDSTATIC="$libdir/libfltk.a $LDLIBS"
+LDSTATIC="'$libdir/libfltk.a' $LDLIBS"
 LDLIBS="-lfltk$SHAREDSUFFIX $LDLIBS"
 
 if test x$use_forms = xyes; then
     LDLIBS="-lfltk_forms$SHAREDSUFFIX $LDLIBS"
-    LDSTATIC="$libdir/libfltk_forms.a $LDSTATIC"
+    LDSTATIC="'$libdir/libfltk_forms.a' $LDSTATIC"
 fi
 
 if test x$use_gl = xyes; then
     LDLIBS="-lfltk_gl$SHAREDSUFFIX $GLLIBS $LDLIBS"
-    LDSTATIC="$libdir/libfltk_gl.a $GLLIBS $LDSTATIC"
+    LDSTATIC="'$libdir/libfltk_gl.a' $GLLIBS $LDSTATIC"
 fi
 
 if test x$use_images = xyes; then
     LDLIBS="-lfltk_images$SHAREDSUFFIX $IMAGELIBS $LDLIBS"
-    LDSTATIC="$libdir/libfltk_images.a $STATICIMAGELIBS $LDSTATIC"
+    LDSTATIC="'$libdir/libfltk_images.a' $STATICIMAGELIBS $LDSTATIC"
 fi
 
 if test x$use_cairo = xyes -a -n "$CAIROLIBS"; then
@@ -327,7 +327,7 @@ if test -n "$compile"; then
     command="$CXX $ARCHFLAGS $includes $CXXFLAGS $debug -o $prog $flags $compile $files $LDSTATIC $link"
 
     echo $command
-    $command || exit 1
+    eval $command || exit 1
 fi
 
 if test -n "$post"; then
@@ -395,7 +395,7 @@ if test "$echo_ldflags" = "yes"; then
     libdirs="$libs"
 
     for i in $LDLIBS ; do
-        if test $i != "-L$libdir" ; then
+        if test $i != "-L'$libdir'" ; then
             if test -z "$my_libs" ; then
                 my_libs="$i"
             else
@@ -411,22 +411,22 @@ if test "$echo_ldstaticflags" = "yes"; then
 fi
 
 if test "$echo_libs" = "yes"; then
-    USELIBS="$libdir/libfltk.a"
+    USELIBS="'$libdir/libfltk.a'"
 
     if test x$use_forms = xyes; then
-        USELIBS="$libdir/libfltk_forms.a $USELIBS"
+        USELIBS="'$libdir/libfltk_forms.a' $USELIBS"
     fi
 
     if test x$use_gl = xyes; then
-        USELIBS="$libdir/libfltk_gl.a $USELIBS"
+        USELIBS="'$libdir/libfltk_gl.a' $USELIBS"
     fi
 
     if test x$use_images = xyes; then
-        USELIBS="$libdir/libfltk_images.a $USELIBS"
+        USELIBS="'$libdir/libfltk_images.a' $USELIBS"
 
         for lib in fltk_jpeg fltk_png fltk_z; do
             if test -f "$libdir/lib$lib.a"; then
-                USELIBS="$libdir/lib$lib.a $USELIBS"
+                USELIBS="'$libdir/lib$lib.a' $USELIBS"
             fi
         done
     fi