configure.in: do not disable ucontext.h

* configure.in (ac_cv_func_{getcontext,setcontext}): do not
  disable ucontext.h entirely, but disable use of functions only.
  `ucontext_t` is necessary in the signal handler now.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46114 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Sun May 25 20:31:49 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* configure.in (ac_cv_func_{getcontext,setcontext}): do not
+	  disable ucontext.h entirely, but disable use of functions only.
+	  `ucontext_t` is necessary in the signal handler now.
+
 Sun May 25 20:00:23 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* signal.c (check_stack_overflow): revert part of r46100, the

configure.in

@@ -969,7 +969,8 @@ AS_CASE(["$target_os"],
 		    [macosx_10_5=yes], [macosx_10_5=no])
 		AC_MSG_RESULT($macosx_10_5)
 		if test $macosx_10_5 = yes; then
-		    ac_cv_header_ucontext_h=no
+		    ac_cv_func_getcontext=no
+		    ac_cv_func_setcontext=no
 		else
 		    AC_DEFINE(BROKEN_SETREUID, 1)
 		    AC_DEFINE(BROKEN_SETREGID, 1)