[Driver][test] pgo-sample-use-profi.c: specify --target=

Some targets (e.g. AIX) report an error for certain unimplemented
features, making Clang exit with 1.

Author: MaskRay

clang/test/Driver/pgo-sample-use-profi.c

@@ -1,4 +1,4 @@
 /// Test if profi flat is enabled in frontend as user-facing feature.
-// RUN: %clang -c -fsample-profile-use-profi -fprofile-sample-use=/dev/null -### %s 2>&1 | FileCheck %s
+// RUN: %clang --target=x86_64 -c -fsample-profile-use-profi -fprofile-sample-use=/dev/null -### %s 2>&1 | FileCheck %s
 
 // CHECK: "-mllvm" "-sample-profile-use-profi"