[clang] Use a specific target when testing that -fomit-frame-pointer and -pg are mutually exclusive (#148000)

Some targets, such as `aarch64-pc-windows-msvc`, always require that
Frame Pointer be reserved even when `-fomit-frame-pointer` is provided,
thus it is always valid to use `-pg` on those targets.

This test didn't take these targets into account; thus it was failing on
Arm64 Windows host machines.

The fix is to explicitly set a target that doesn't require Frame
Pointers reservation.

Author: dpaoliello

clang/test/Driver/frame-pointer-elim.c

@@ -44,8 +44,8 @@
 // RUN:   FileCheck --check-prefix=KEEP-NONE %s
 
 // -pg -fomit-frame-pointer => error.
-// RUN: not %clang -### -S -fomit-frame-pointer -pg %s 2>&1 | FileCheck -check-prefix=CHECK-NO-MIX-OMIT-FP-PG %s
-// RUN: %clang -### -S -fomit-frame-pointer -fno-omit-frame-pointer -pg %s 2>&1 | FileCheck -check-prefix=CHECK-MIX-NO-OMIT-FP-PG %s
+// RUN: not %clang -### --target=i386-linux -S -fomit-frame-pointer -pg %s 2>&1 | FileCheck -check-prefix=CHECK-NO-MIX-OMIT-FP-PG %s
+// RUN: %clang -### --target=i386-linux -S -fomit-frame-pointer -fno-omit-frame-pointer -pg %s 2>&1 | FileCheck -check-prefix=CHECK-MIX-NO-OMIT-FP-PG %s
 // CHECK-NO-MIX-OMIT-FP-PG: '-fomit-frame-pointer' not allowed with '-pg'
 // CHECK-MIX-NO-OMIT-FP-PG-NOT: '-fomit-frame-pointer' not allowed with '-pg'