Work around stack frame size for memtag-stack

The root cause for the warning is fixed in upstream LLVM
(https://reviews.llvm.org/D127917) , working around until
that is submitted.

Test: make libc with memtag-stack
Bug: 174878242
Change-Id: Iae8c85f39bdceb9752b7f2758c5543c1b3f90277