[BuildLibCalls] Add noalias for strcat and stpcpy

strcat:
destination and source shall not overlap. (http://www.cplusplus.com/reference/cstring/strcat/)

stpcpy:
The strings may not overlap, and the destination string dest must be  large enough to receive the copy. (https://man7.org/linux/man-pages/man3/stpcpy.3.html)

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D88335