[llvm] [CGP] Consider arguments and ret values in `dupRetToEnableTailCallOpts` (PR #76613)

[Antonio Frighetto via llvm-commits]

antoniofrighetto wrote:

@dtcxzyw, thanks, restrained the folding to ret values of function calls and function arguments, and considering essentially only libc functions (whose first argument coincides with the return value).

https://github.com/llvm/llvm-project/pull/76613