[compiler-rt] [compiler-rt][builtins] Switch to using __builtin_memcpy_inline (PR #69784)

[Alexander Shaposhnikov via llvm-commits]

alexander-shaposhnikov wrote:

__builtin_bit_cast seems to be available only in C++ (https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html), not in C

https://github.com/llvm/llvm-project/pull/69784