Ruby: inform autoconf where the private (elf32/elf64) headers are.

Now the build fails because SIGBUS is undeclared...

dev-lang/ruby/ruby-1.9.3.recipe

@@ -19,7 +19,7 @@ LICENSE="Ruby
 	Artistic (Perl)
 	BSD (3-clause)"
 COPYRIGHT="1993-2009 Yukihiro Matsumoto"
-REVISION="3"
+REVISION="4"
 ARCHITECTURES="x86 ?x86_64"
 if [ $effectiveTargetArchitecture != x86_gcc2 ]; then
     # x86_gcc2 is fine as primary target architecture as long as we're building
@@ -71,6 +71,7 @@ BUILD_REQUIRES="
 	devel:libiconv$secondaryArchSuffix
 	devel:libncursesw$secondaryArchSuffix
 	cmd:pkg_config$secondaryArchSuffix
+	cmd:ruby >= 1.9
 	"
 
 BUILD_PREREQUIRES="
@@ -96,8 +97,17 @@ REQUIRES_devel="
 BUILD()
 {
 	autoconf
+	
+	# tell configure where to find the private header folders
+	# that have elf32.h and elf64.h
+	if [ $effectiveTargetArchitecture != x86_gcc2 ]; then
+	    extraFlags="-I/boot/system/develop/headers/private/system"
+	else
+	    extraFlags="-I/boot/system/develop/headers/private/system/arch/x86"
+	fi
+
 	runConfigure ./configure \
-		--enable-shared
+		--enable-shared CFLAGS="$extraFlags" CXXFLAGS="$extraFlags"
 	make $jobArgs
 }
 
@@ -105,6 +115,7 @@ INSTALL()
 {
 	make install
 	prepareInstalledDevelLibs libruby-static libruby
+	fixPkgconfig
 	packageEntries devel $developDir
 }