Improvements to recent parallelism changes:
1. BLIS specific threading options: In bli_thread_update_rntm_from_env()
set threading variables in tl_rntm to serial values when OpenMP level
for parallelism within BLIS will not be active. User supplied BLIS
threading values remain unchanged in global_rntm.
2. Simplify code structure in bli_thread_update_rntm_from_env().
3. Change variable declarations in bli_thread_init_rntm_from_env()
and bli_thread_update_rntm_from_env() to avoid unused variable
warnings in non-OpenMP builds.
AMD-Internal: [CPUPL-2433]
Change-Id: I5505657e3d2722e69bc4a1c1bb9fd8df55407fdd
345aacf806