in response to compile-time warning from #2551

MIPS 32-bit currently has an empty blas_lock implementation which is
worse than nothing at all. MIPS 64-bit does has a blas_lock
implementation but is broken. Remove them and fallback to the generic
version in common.h which should do the right thing on MIPS.

The MIPS architecture has weak memory ordering and therefore requires
sutible memory barriers when doing lock free programming with multiple
threads (just like ARM does). This commit implements those barriers for
MIPS and MIPS64 using GCC bultins which is probably easiest way.

.func/.endfunc are gcc/gas-specific directives for generating stabs
debug information (and nothing more). This is near-useless now because
DWARF is commonly used, and not implemented in Clang. Hence building
OpenBLAS with Clang fails, and there is no sane way to detect GCC vs.
anything else with preprocessor definitions.

Hence, just remove these directives.

Seperated mips and mips64 files.
Configurations support for mips 32 bit.

Signed-off-by: Shivraj Patil <shivraj.patil@imgtec.com>