ruby: remove references to the cross compiler from rbconfig.rb.

Fixes building gems natively on ARM.

srcpkgs/ruby/template

@@ -3,7 +3,7 @@ _ruby_abiver=2.1.0
 
 pkgname=ruby
 version=2.1.5
-revision=1
+revision=2
 build_style=gnu-configure
 configure_args="--enable-shared --disable-rpath
  DOXYGEN=/usr/bin/doxygen DOT=/usr/bin/dot PKG_CONFIG=/usr/bin/pkg-config"
@@ -26,6 +26,12 @@ pre_build() {
 	# Force getaddrinfo detection.
 	sed -e 's,\(checking_for("wide getaddrinfo") {try_\)run,\1link,' -i ext/socket/extconf.rb
 }
+post_install() {
+	# Remove references to the cross compiler
+	if [ "$CROSS_BUILD" ]; then
+		sed -e "s,${XBPS_CROSS_TRIPLET}-,,g" -i ${DESTDIR}/usr/lib/ruby/${_ruby_abiver}/*/rbconfig.rb
+	fi
+}
 
 ruby-devel-docs_package() {
 	short_desc+=" - HTML C API documentation files"