configure should check for warning flags supported to disable them (#338205).

Configure would check whether gcc supported -Wno... flags. But gcc always
does. It is happy to just not warn about anything. So flip all configure
checks to test for the warning and only when gcc accepts the warning flag
use -Wno-...

Introduces two helper functions to make it easier to add new flag checks.
AC_GCC_WARNING_COND and AC_GCC_WARNING_SUBST_NO.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14319 a5019735-40e9-0310-863c-91ae7b9d1cf9
Kind of a follow-up to r14237.
pre_mem_read_sockaddr: in the case where the caller doesn't
specify any address family (that is, the family is AF_UNSPEC)
don't perform any further checks on the supplied |sa| address
block, since doing so merely gives rise to false uninitialised
value errors.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14320 a5019735-40e9-0310-863c-91ae7b9d1cf9
Remove unused functions CLG_(get_out_file) and CLG_(get_out_directory).
Looks like these were leftovers from early days -- perhaps r7235.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14321 a5019735-40e9-0310-863c-91ae7b9d1cf9
Update in NEWS the gcc release needed to better support Ada tasks termination


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14322 a5019735-40e9-0310-863c-91ae7b9d1cf9
Clean up confusion about VG_(args_the_exename) which was believed to
possibly be NULL in several places. Nowadays, VG_(ii_create_image) will
terminate the process if VG_(args_the_exename) is NULL.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14323 a5019735-40e9-0310-863c-91ae7b9d1cf9
Improve -mpreferred-stack-boundary configure message.

Explicitly say we are checking for -mpreferred-stack-boundary=2.
Only 2 is ever used when it is supported. Some gcc versions/arches
(e.g. GCC 4.8 for x86_64) support -mpreferred-stack-boundary, but
only between 4 and 12. The message that -mpreferred-stack-boundary
wasn't supported was a little confusing. So explicitly say we checked
for -mpreferred-stack-boundary=2.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14324 a5019735-40e9-0310-863c-91ae7b9d1cf9
Check some known PATHs for mpicc in configure.

On some distributions (fedora) mpicc not installed on the default PATH.
Add a search path for finding mpicc by default if it is installed.
The user can still override the used mpicc compiler using --with-mpicc=.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14325 a5019735-40e9-0310-863c-91ae7b9d1cf9
exp-sgcheck/tests/hackedbz2.c mark vex_strlen as noinline

Explicitly set noinline so the test can check it is in the backtrace.
Newer gcc versions happily optimize it away otherwise.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14326 a5019735-40e9-0310-863c-91ae7b9d1cf9
Bug 338445 amd64 vbit-test fails with unknown opcodes used by arm64 VEX.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14327 a5019735-40e9-0310-863c-91ae7b9d1cf9
NEWS 330319 vex amd64->IR: unhandled instruction bytes: 0xF 0x1 0xD5 (xend)

VEX svn r2931

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14328 a5019735-40e9-0310-863c-91ae7b9d1cf9
Follow up to r14313: disable stack cache earlier
glibc is recycling memory for detached threads before a thread
termination => disable the stack cache earlier (i.e. once
a 'non main thread' is seen)



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14329 a5019735-40e9-0310-863c-91ae7b9d1cf9