v23.01 release

• Project changes
  • All files are under a new dual license now (MIT OR Apache-2.0 WITH LLVM-exception at the election of the user).
  • Added MAINTAINERS file describing who maintains the subdirectories.
  • Added README.contributors files documenting contribution requirements.
  • Added new pl/ subdirectory for Arm's Performance Library related routines.
• String routine changes
  • Added memset benchmark.
  • Improved strlen and memcpy benchmarks.
  • Added SVE memcpy.
  • Updated arm string functions to support M-profile PACBTI.
  • Merged the MTE and generic versions of strcmp, strncmp, strcpy and stpcpy into one implementation.
  • Optimized memcmp, memchr-mte, memrchr, strchr-mte, strchrnul-mte, strrchr-mte, strlen, strlen-mte, strnlen, strcpy.
• Math routine changes
  • Fixed constants in sinf, cosf and sincosf to be compile time computed even with gcc-12 -frounding-math.
  • Fixed an invalid shift in logf.
  • Support floating-point exceptions in vector math routines when WANT_SIMD_EXCEPT is set.