While working on the strstr patch I noticed several copyright headers
of the new math functions are missing closing quotes after ``AS IS.
I've added these. Also update spellings of Arm Ltd in a few places
(but still use ARM LTD in upper case portion). Finally add SPDX
identifiers to make everything consistent.
The new implementation is provided under !__OBSOLETE_MATH, it uses
ISO C99 code. With default settings the worst case error in nearest
rounding mode is 0.54 ULP with inlined fma and fma contraction. It uses
a 4 KB lookup table in addition to the table in exp_data.c, on aarch64
.text+.rodata size of libm.a is increased by 2295 bytes.
Improvements on Cortex-A72:
latency: 3.3x
thruput: 4.9x