[glibc] powerpc: Fix -mlong-double-128 IBM format configure test for Clang

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=559d0f77f3ee1000cf8a2d0baba7a59a1ec45f50

commit 559d0f77f3ee1000cf8a2d0baba7a59a1ec45f50
Author: Matt Turner <[email protected]>
Date:   Sun Jul 26 14:43:11 2026 -0400

    powerpc: Fix -mlong-double-128 IBM format configure test for Clang
    
    The check for -mlong-double-128 IBM extended format support wrapped its
    test code in AC_LANG_PROGRAM, which places the body inside main().  The
    body defines a function, so it became a nested function definition -- a
    GCC extension that Clang does not implement, making the test fail with
    Clang.
    
    Use AC_LANG_SOURCE so the function is defined at file scope, and
    regenerate configure.
    
    Reviewed-by: Sam James <[email protected]>

Diff:
---
 sysdeps/unix/sysv/linux/powerpc/configure    | 8 +-------
 sysdeps/unix/sysv/linux/powerpc/configure.ac | 3 ++-
 2 files changed, 3 insertions(+), 8 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/powerpc/configure b/sysdeps/unix/sysv/linux/powerpc/configure
index ef2055db92..eb8578404f 100644
--- a/sysdeps/unix/sysv/linux/powerpc/configure
+++ b/sysdeps/unix/sysv/linux/powerpc/configure
@@ -12,18 +12,12 @@ else case e in #(
 CFLAGS="$CFLAGS -mlong-double-128"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
-#include <float.h>
-int
-main (void)
-{
 
+#include <float.h>
 #if LDBL_MANT_DIG != 106
 # error "compiler doesn't implement IBM extended format of long double"
 #endif
 long double foobar (long double x) { return x; }
-  ;
-  return 0;
-}
 _ACEOF
 if ac_fn_c_try_compile "$LINENO"
 then :
diff --git a/sysdeps/unix/sysv/linux/powerpc/configure.ac b/sysdeps/unix/sysv/linux/powerpc/configure.ac
index 42347a66fc..ca0f82da08 100644
--- a/sysdeps/unix/sysv/linux/powerpc/configure.ac
+++ b/sysdeps/unix/sysv/linux/powerpc/configure.ac
@@ -6,7 +6,8 @@ AC_CACHE_CHECK(whether $CC $CFLAGS -mlong-double-128 uses IBM extended format,
 	       libc_cv_mlong_double_128ibm, [dnl
 save_CFLAGS="$CFLAGS"
 CFLAGS="$CFLAGS -mlong-double-128"
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <float.h>]], [[
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+#include <float.h>
 #if LDBL_MANT_DIG != 106
 # error "compiler doesn't implement IBM extended format of long double"
 #endif