Merge pull request #38 from github/backport_high_sierra_fix

Backport r60182 to fix High Sierra issues

Author: Charlie Somerville

configure.in

@@ -4142,8 +4142,8 @@ AS_CASE(["$target_os"],
 	],
     [darwin*], [
 	RUBY_APPEND_OPTION(CFLAGS, -pipe)
-	RUBY_APPEND_OPTION(XLDFLAGS, [-framework CoreFoundation])
-	RUBY_APPEND_OPTION(LIBRUBYARG_STATIC, [-framework CoreFoundation])
+	RUBY_APPEND_OPTION(XLDFLAGS, [-framework Foundation])
+	RUBY_APPEND_OPTION(LIBRUBYARG_STATIC, [-framework Foundation])
 	],
     [osf*], [
 	if test "$GCC" != "yes" ; then