[compiler-rt] [test] [profile] Mark the without-libc test as unsupported on mingw

[mstorsjo]

Summary

Mingw toolchains always end up referencing the malloc symbol due to
the CRT startup files.

compiler-rt/test/profile/instrprof-without-libc.c

 // RUN: %clang_profgen -DCHECK_SYMBOLS -O3 -o %t.symbols %s
 // RUN: llvm-nm %t.symbols | FileCheck %s --check-prefix=CHECK-SYMBOLS
 // RUN: %clang_profgen -O3 -o %t %s
 // RUN: %run %t %t.profraw
 // RUN: llvm-profdata merge -o %t.profdata %t.profraw
 // RUN: %clang_profuse=%t.profdata -o - -S -emit-llvm %s | FileCheck %s
 
 // This usage of llvm-nm assumes executables have symbol tables. They do not in
 // an MSVC environment, so we can't make this test portable.
 // UNSUPPORTED: target={{.*msvc.*}}
 
+// The MinGW CRT init files do reference malloc etc, so this test fails.
+// UNSUPPORTED: target={{.*windows-gnu.*}}
+
 #include <stdint.h>
 #include <stdlib.h>
 
 #ifndef CHECK_SYMBOLS
 #include <stdio.h>
 #endif
 
 int __llvm_profile_runtime = 0;