[profile] Test error reporting by writing to a temp directory

This test case is meant to check whether verbose error logging works. It
does this by _failing_ to write a profile to a path corresponding to a
directory. Make this clearer by writing to a temporary directory.

Patch suggested by Sean Silva!

llvm-svn: 264817

compiler-rt/test/profile/instrprof-error.c

@@ -1,5 +1,5 @@
 // RUN: %clang_profgen -o %t -O3 %s
-// RUN: env LLVM_PROFILE_FILE="/" LLVM_PROFILE_VERBOSE_ERRORS=1 %run %t 1 2>&1 | FileCheck %s
+// RUN: env LLVM_PROFILE_FILE="%t/" LLVM_PROFILE_VERBOSE_ERRORS=1 %run %t 1 2>&1 | FileCheck %s
 
 int main(int argc, const char *argv[]) {
   if (argc < 2)