As shown in #2538, default buffersizes on some platforms were smaller than required in memory.c
and the requirement could never be fulfilled for a calculated GEMM_R on PPC given the fomula used

If ARM abi is not explicitly mentioned on the command line, then set the
arm abi to softfp or hard according to the compiler environment.
This assumes that compiler sets the defines __ARM_PCS and __ARM_PCS_VFP
accordingly.

.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.

there is no more requirement for ARMv6 instructions,
and VFP on ARMv5 is uncommon

to be used on armv5 and new platforms

otherwise some macros like YIELDING are not defined correctly

- use on arm, arm64 and any new platform
- use faster integer math instead of double
- use similar scale as rdtsc so that timeouts work

- was writing 0 to lock variable, so was ineffective
- only exit loop if both lock was 0 and strex was successful

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