fix r37904: it forced i486 though -marh was usually i686

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37906 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -5,7 +5,7 @@ Wed Nov 28 03:03:28 2012  NARUSE, Yui  <naruse@ruby-lang.org>
 Wed Nov 28 02:55:35 2012  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* configure.in (ARCH_FLAG): __sync_val_compare_and_swap_4 needs
-	  -march=i486 on at least linux gcc 4.1.
+	  -march=$target_cpu on at least linux gcc 4.1.
 
 Tue Nov 27 22:03:09 2012  Akinori MUSHA  <knu@iDaemons.org>
 

configure.in

@@ -243,7 +243,7 @@ AC_DEFUN([RUBY_DEFAULT_ARCH], [
 AC_MSG_CHECKING([arch option])
 AS_CASE([$1-$target_os],
 	[*64-*],        [ARCH_FLAG=-m64],
-	[[i[3-6]86-linux]], [ARCH_FLAG=-march=i486],
+	[[i[3-6]86-linux]], [ARCH_FLAG=-march=$1],
 	[[i[3-6]86-*]], [ARCH_FLAG=-m32],
 	[AC_MSG_ERROR(unknown target architecture: $target_archs)]
 	)