Close shmem file handle, to fix file handle leak

kfdtest hsaKmtOpenKFD failed after 1019 loop if using --gtest_loop=-1,
because default max open file handle limit is 1024. Found shmem file handle
is not closed from lsof output.

Change-Id: I474de2bae6c03e879a219dedf5f18639118b73e5
Signed-off-by: Philip Yang <Philip.Yang@amd.com>

src/perfctr.c

@@ -149,8 +149,11 @@ static void destroy_shared_region(void)
 	if (shared_table && shared_table != MAP_FAILED)
 		munmap(shared_table, sizeof(*shared_table));
 
-	if (shmem_fd > 0)
+	if (shmem_fd > 0) {
+		close(shmem_fd);
 		shm_unlink(shmem_name);
+	}
+
 	if (sem != SEM_FAILED) {
 		sem_close(sem);
 		sem_unlink(sem_name);