Prevent adding module flag amdgpu_hostcall multiple times

HIP program with printf call fails to compile with -fsanitize=address
option, because of appending module flag - amdgpu_hostcall twice, one
for printf and one for sanitize option. This patch fixes that issue.

Patch by: Praveen Velliengiri

Reviewed by: Yaxun Liu, Roman Lebedev

Differential Revision: https://reviews.llvm.org/D116216