Define `HAVE___BUILTIN_UNREACHABLE` instead of `UNREACHABLE`

`UNREACHABLE` in ruby/internal/has/builtin.h is only used as just
a flag now, and redefined in ruby/backward/2/assume.h then.

1 files changed, 1 insertions, 1 deletions

diff --git a/configure.ac b/configure.ac
index 4b8dce1a2f..916e9a4e98 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1677,7 +1677,7 @@ AS_IF([test "$GCC" = yes], [
     ])
     ])
     AS_IF([test "$rb_cv_func___builtin_unreachable" = yes], [
-	AC_DEFINE_UNQUOTED(UNREACHABLE, [__builtin_unreachable()])
+	AC_DEFINE(HAVE___BUILTIN_UNREACHABLE)
     ])
 }