configure.in: do not use a variable for longjmp

* configure.in (ac_cv_func___builtin_setjmp): gcc 4.9 disallows a
  variable as the second argument of __builtin_longjmp().
  [ruby-core:61800] [Bug #9692]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45503 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Wed Apr  2 17:43:17 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* configure.in (ac_cv_func___builtin_setjmp): gcc 4.9 disallows a
+	  variable as the second argument of __builtin_longjmp().
+	  [ruby-core:61800] [Bug #9692]
+
 Wed Apr  2 15:12:18 2014  SHIBATA Hiroshi  <shibata.hiroshi@gmail.com>
 
 	* common.mk: Use redmine-2.x url for DeveloperHowto wiki.

configure.in

@@ -2076,8 +2076,13 @@ AC_CACHE_CHECK(for sigsetjmp as a macro or function, ac_cv_func_sigsetjmp,
 
 AC_CACHE_CHECK(for __builtin_setjmp, ac_cv_func___builtin_setjmp,
 [AC_TRY_LINK([@%:@include <setjmp.h>
-    jmp_buf jb; void t(v) int v; {__builtin_longjmp(jb, v);}],
-    [__builtin_setjmp(jb);],
+    @%:@include <stdio.h>
+    jmp_buf jb;
+    void t(void) {__builtin_longjmp(jb, 1);}],
+    [
+    void (*volatile f)(void) = t;
+    if (!__builtin_setjmp(jb)) printf("%d\n", f != 0);
+    ],
     [ac_cv_func___builtin_setjmp=yes],
     [ac_cv_func___builtin_setjmp=no])
 ])