This patch refactor ARM memcpy ifunc selector to a C implementation.
No functional change is expected, including ifunc resolution rules.
It also adds some cleanup:
- Internal memcpy hidden definition (__GI_memcpy) is now a hidden
symbol.
- No need to create hidden definition for the ifunc variants.
Checked on armv7-linux-gnueabihf and with a build for arm-linux-gnueabi,
arm-linux-gnueabihf with and without multiarch support and with both
GCC 7.1 and GCC mainline. I also checked with the some possible
multiarch different configurations that trigger different memcpy
buids (__ARM_NEON__ && !__SOFT_FP__, !__ARM_NEON__ && !__SOFT_FP__, and
!__ARM_NEON__ && __SOFT_FP__).