Fix race condition during shutdown causing a crash in
gotoblas_set_affinity().

get_nprocs() is a GNU convenience function equivalent to POSIX2008
sysconf(_SC_NPROCESSORS_ONLN); the latter should be available in unistd.h
on any current *nix. (OS X supports this call since 10.5, and FreeBSD
currently supports it. But this commit does not change FreeBSD or OS X
versions.)

The user can use char * openblas_get_config() or char * openblas_get_corename().

Conflicts:
	driver/others/memory.c

Signed-off-by: Timothy Gu <timothygu99@gmail.com>

This reverts commit 3617c22a56.

The problem is the mutex we used in blas_server. Thus, we must clear
the mutex before the fork and re-init them at parent and child process.

If you used OpenMP, GOMP has the same problem by now. Please try other OpenMP
implemantation.

By default, OpenBLAS doesn't output the warning message. You can set
OPENBLAS_VERBOSE (e.g. export OPENBLAS_VERBOSE=1) to enable the warning
message on runtime.

The present patch verifies that, on machines declaring an Athlon CPU model and
family, the 3dnow and 3dnowext feature flags are indeed present. If they are
not, it fallbacks on the most generic x86 kernel. This prevents crashes due to
illegal instruction on qemu guests with a weird configuration.

Closes #272