util: Move __stdlib_compat to function definitions

Putting a visibility-hidden attribute in the header file
is ambiguous. The compiler cannot determine which definition
should be hidden (our implementation or stdlib).

This serves as a slight correction to the work in crrev.com/c/1180401 .
In particular, this fixes test/fuzz builds with code coverage enabled:
make runtests TEST_COVERAGE=1 -j

Before this fix, enabling coverage would trigger build errors,
like the following:

In file included from common/test_util.c:19:
include/util.h:82:1: error: attribute declaration must precede definition [-Werror,-Wignored-attributes]
__stdlib_compat int atoi(const char *nptr);
^
include/common.h:267:40: note: expanded from macro '__stdlib_compat'
#define __stdlib_compat __attribute__((visibility("hidden")))
                                       ^
/usr/include/stdlib.h:361:8: note: previous definition is here
__NTH (atoi (const char *__nptr))

Note that enabling sanitizer on some unit tests is still broken
(as it was before this CL). For example, these unit tests fail
when compiling with sanitizers:
make host-charge_manager_drp_charging TEST_ASAN=1
make host-charge_manager_drp_charging TEST_MSAN=1

BRANCH=none
BUG=none
TEST=make runtests TEST_COVERAGE=1 -j
TEST=make buildall -j

Change-Id: I74462c964c0ff9d3ee131450e6826cbbd6c89319
Signed-off-by: Craig Hesling <hesling@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1724936
Reviewed-by: Aseda Aboagye <aaboagye@chromium.org>
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/trng.h b/include/trng.h
index e50b12a2a6..cea4555b41 100644
--- a/include/trng.h
+++ b/include/trng.h
@@ -32,7 +32,7 @@ void exit_trng(void);
  * Not supported on all platforms.
  **/
 #ifndef HIDE_EC_STDLIB
-__stdlib_compat uint32_t rand(void);
+uint32_t rand(void);
 #endif
 
 /**