Restore __builtin_assume following compiler fix.
Restore __builtin_assume following compiler fix.

https://github.com/llvm/llvm-project/commit/6d20937c29a1 enables tail calls
in the presence of assume.

PiperOrigin-RevId: 306448232
Change-Id: Ib548d93fb9f98c668cb885db9771e89b478e9d07

google/tcmalloc,google/tcmalloc,google/tcmalloc