Disable libcall optimizations for wrappers of memory allocation functions

[davidbolvansky]

Fixes #3584

I was able to compile p4c with Clang 12.

[davidbolvansky]

For future readers:
If this somehow breaks again in the future (I believe that this should work fine with LTO or unity builds as well), you can try a bigger hammer:
set (P4C_CXX_FLAGS "-fno-builtin")

[davidbolvansky]

cc @mbudiu-vmw @ChrisDodd

I believe this fix is better than #3585 as that can be again defeated by more inlining done by cpp compiler.

[davidbolvansky]

Later (if project maintainers consider this useful) I can extend current github actions to build and test p4c with clang as well.

[mihaibudiu]

I can't test this but I will approve it.

[davidbolvansky]

Ok thanks, you can merge it