[libFuzzer] Disable Msan on InternalStrnlen

It's called from ATTRIBUTE_NO_SANITIZE_MEMORY code.
It worked as expected if inlined and complained otherwise.

Reviewed By: eugenis

Differential Revision: https://reviews.llvm.org/D113323

GitOrigin-RevId: 3c7960cba19ed926b8e86b4c619e81c0f7da4d15
1 file changed