[gcc(refs/users/meissner/heads/work029)] PowerPC: Allow configuring older glibcs for IEEE 128-bit float.

[Michael Meissner <meissner@gcc.gnu.org>]

https://gcc.gnu.org/g:5e732b39fb73b5d4e2e3343dc15803e286980678

commit 5e732b39fb73b5d4e2e3343dc15803e286980678
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Thu Dec 10 15:00:20 2020 -0500

    PowerPC: Allow configuring older glibcs for IEEE 128-bit float.
    
    libstdc++-v3/
    2020-12-10  Michael Meissner  <meissner@linux.ibm.com>
    
            * configure.ac (powerpc*-*-linux*): Check for __frexpieee128
            instead of frexpf128, so that older GLIBCs can be used.
            * configure: Regenerate.

Diff:
---
 libstdc++-v3/configure    | 20 ++++++++++----------
 libstdc++-v3/configure.ac |  2 +-
 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
index 26035d6a4ee..6776b1a0d84 100755
--- a/libstdc++-v3/configure
+++ b/libstdc++-v3/configure
@@ -75722,9 +75722,9 @@ $as_echo "#define _GLIBCXX_LONG_DOUBLE_COMPAT 1" >>confdefs.h
       powerpc*-*-linux*)
 	LONG_DOUBLE_COMPAT_FLAGS="$LONG_DOUBLE_COMPAT_FLAGS -mno-gnu-attribute"
         # Check for IEEE128 support in libm:
-        { $as_echo "$as_me:${as_lineno-$LINENO}: checking for frexpf128 in -lm" >&5
-$as_echo_n "checking for frexpf128 in -lm... " >&6; }
-if ${ac_cv_lib_m_frexpf128+:} false; then :
+        { $as_echo "$as_me:${as_lineno-$LINENO}: checking for __frexpieee128 in -lm" >&5
+$as_echo_n "checking for __frexpieee128 in -lm... " >&6; }
+if ${ac_cv_lib_m___frexpieee128+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
@@ -75741,27 +75741,27 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 #ifdef __cplusplus
 extern "C"
 #endif
-char frexpf128 ();
+char __frexpieee128 ();
 int
 main ()
 {
-return frexpf128 ();
+return __frexpieee128 ();
   ;
   return 0;
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_m_frexpf128=yes
+  ac_cv_lib_m___frexpieee128=yes
 else
-  ac_cv_lib_m_frexpf128=no
+  ac_cv_lib_m___frexpieee128=no
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_m_frexpf128" >&5
-$as_echo "$ac_cv_lib_m_frexpf128" >&6; }
-if test "x$ac_cv_lib_m_frexpf128" = xyes; then :
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_m___frexpieee128" >&5
+$as_echo "$ac_cv_lib_m___frexpieee128" >&6; }
+if test "x$ac_cv_lib_m___frexpieee128" = xyes; then :
   ac_ldbl_ieee128_in_libc=yes
 else
   ac_ldbl_ieee128_in_libc=no
diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac
index d25842fef35..1c948f9b874 100644
--- a/libstdc++-v3/configure.ac
+++ b/libstdc++-v3/configure.ac
@@ -427,7 +427,7 @@ case "$target" in
       powerpc*-*-linux*)
 	LONG_DOUBLE_COMPAT_FLAGS="$LONG_DOUBLE_COMPAT_FLAGS -mno-gnu-attribute"
         # Check for IEEE128 support in libm:
-        AC_CHECK_LIB(m, frexpf128,
+        AC_CHECK_LIB(m, __frexpieee128,
                      [ac_ldbl_ieee128_in_libc=yes],
                      [ac_ldbl_ieee128_in_libc=no])
         if test $ac_ldbl_ieee128_in_libc = yes; then