[COMMITTED] aarch64: fix SVE ACLE check for bootstrap glibc builds

[Szabolcs Nagy]

arm_sve.h depends on stdint.h but that relies on libc headers unless
compiled in freestanding mode.  Without this change a bootstrap glibc
build (that uses a compiler without installed libc headers) failed with

checking for availability of SVE ACLE... In file included from [...]/arm_sve.h:28,
                 from conftest.c:1:
[...]/stdint.h:9:16: fatal error: stdint.h: No such file or directory
    9 | # include_next <stdint.h>
      |                ^~~~~~~~~~
compilation terminated.
configure: error: mathvec is enabled but compiler does not have SVE ACLE. [...]
---
 sysdeps/aarch64/configure    | 2 +-
 sysdeps/aarch64/configure.ac | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/sysdeps/aarch64/configure b/sysdeps/aarch64/configure
index 22ed9d38d2..d0d78d69f1 100644
--- a/sysdeps/aarch64/configure
+++ b/sysdeps/aarch64/configure
@@ -342,7 +342,7 @@ else
     cat > conftest.c <<EOF
 #include <arm_sve.h>
 EOF
-    if ! ${CC-cc} conftest.c -fsyntax-only; then
+    if ! ${CC-cc} conftest.c -fsyntax-only -ffreestanding; then
       as_fn_error 1 "mathvec is enabled but compiler does not have SVE ACLE. Either use a compatible compiler or configure with --disable-mathvec (this results in incomplete ABI)."
     fi
     rm conftest.c
diff --git a/sysdeps/aarch64/configure.ac b/sysdeps/aarch64/configure.ac
index ba519c9053..259edc3de8 100644
--- a/sysdeps/aarch64/configure.ac
+++ b/sysdeps/aarch64/configure.ac
@@ -112,7 +112,7 @@ AC_CACHE_CHECK(for availability of SVE ACLE, libc_cv_has_sve_acle, [dnl
     cat > conftest.c <<EOF
 #include <arm_sve.h>
 EOF
-    if ! ${CC-cc} conftest.c -fsyntax-only; then
+    if ! ${CC-cc} conftest.c -fsyntax-only -ffreestanding; then
       as_fn_error 1 "mathvec is enabled but compiler does not have SVE ACLE. Either use a compatible compiler or configure with --disable-mathvec (this results in incomplete ABI)."
     fi
     rm conftest.c
-- 
2.25.1