Fix elf/loadtest.c build with GCC 8.
Building the testsuite with current GCC mainline fails with:
loadtest.c: In function 'main':
loadtest.c:76:3: error: macro expands to multiple statements [-Werror=multistatement-macros]
for (map = MAPS; map != NULL; map = map->l_next) \
^
loadtest.c:165:2: note: in expansion of macro 'OUT'
OUT;
^~~
loadtest.c:164:7: note: some parts of macro expansion are not guarded by this 'if' clause
if (debug)
^~
This seems like a genuine bug, although fairly harmless; it means the
fflush call in the OUT macro is unconditional instead of being inside
the conditional as presumably intended. This patch makes this macro
use do { } while (0) to avoid the problem.
Tested for x86_64 (testsuite), and with build-many-glibcs.py for
aarch64-linux-gnu with GCC mainline.
* elf/loadtest.c (OUT): Define using do { } while (0).