[glibc/azanella/clang] configure: Fix check for -fno-tree-loop-distribute-patterns

[Adhemerval Zanella <azanella@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=ffcaa3c6710fbaec084b8c66e3f480ef50aaf311

commit ffcaa3c6710fbaec084b8c66e3f480ef50aaf311
Author: Fangrui Song <maskray@google.com>
Date:   Sun Sep 26 00:15:23 2021 -0700

    configure: Fix check for -fno-tree-loop-distribute-patterns
    
    clang does not support -fno-tree-loop-distribute-patterns and using
    on __attribute__ ((__optimize__ (...))) only triggers a warning
    with AC_TRY_COMMAND.  Add -Werror so the tests fails if compiler
    does not support it.

Diff:
---
 configure    | 2 +-
 configure.ac | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/configure b/configure
index 45ee893d49..85226db392 100755
--- a/configure
+++ b/configure
@@ -7402,7 +7402,7 @@ __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
 foo (void) {}
 EOF
 libc_cv_cc_loop_to_function=no
-if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -c conftest.c'
+if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -Werror -c conftest.c'
   { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
   (eval $ac_try) 2>&5
   ac_status=$?
diff --git a/configure.ac b/configure.ac
index 7a7fe4a28a..f508411c25 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1504,7 +1504,7 @@ __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
 foo (void) {}
 EOF
 libc_cv_cc_loop_to_function=no
-if AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -c conftest.c])
+if AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -Werror -c conftest.c])
 then
   libc_cv_cc_loop_to_function=yes
 fi