Use M_PI_34l consistently in libm-test.inc.
Fix tst-mutexpi8

2013-05-09  Andi Kleen  <ak@linux.intel.com>

	* tst-mutex8.c (do_test): Check for ENABLE_PI.
Use M_SQRT1_2l instead of local M_SQRT_2_2 in libm-test.inc.