Loongarch: Add ifunc support for memcpy{aligned, unaligned, lsx, lasx} and memmove...

Loongarch: Add ifunc support for memcpy{aligned, unaligned, lsx, lasx} and memmove{aligned, unaligned, lsx, lasx}

These implementations improve the time to copy data in the glibc
microbenchmark as below:
memcpy-lasx       reduces the runtime about 8%-76%
memcpy-lsx        reduces the runtime about 8%-72%
memcpy-unaligned  reduces the runtime of unaligned data copying up to 40%
memcpy-aligned    reduece the runtime of unaligned data copying up to 25%
memmove-lasx      reduces the runtime about 20%-73%
memmove-lsx       reduces the runtime about 50%
memmove-unaligned reduces the runtime of unaligned data moving up to 40%
memmove-aligned   reduces the runtime of unaligned data moving up to 25%