counters: fix 2 scan-build warnings

counters.c:1069:13: warning: Potential leak of memory pointed to by 'temp'
            SCMutexUnlock(&sc_perf_op_ctx->pctmi_lock);
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./threads.h:121:28: note: expanded from macro 'SCMutexUnlock'
                           ^~~~~~~~~~~~~~~~~~~~
counters.c:1156:16: warning: Potential leak of memory pointed to by 'pca'
        return NULL;
               ^~~~
/usr/include/clang/3.3/include/stddef.h:77:24: note: expanded from macro 'NULL'
                       ^
2 warnings generated.
Fix PmqSetup() argument removal in ac-tile MPM unit tests.

Needed to remove the second argument from all the calls, which was always 0
and was removed in other tests in a previous checkin.
Remove GCC -no-strict-aliasing compiler flag.

GCC typically generates better code without the -no-strict-aliasing flag.
It is only required if code makes assumptiosn that break strict aliasing.
The unit tests pass on x86 and Tile without the flag.