Remove HAVE_LIBPSAPI, HAVE_SHELL32.

These used to be set in the old autoconf build, but the cmake build has had a
"TODO: actually check for these" comment since it was checked in, and they
were set to 1 on mingw unconditionally.  It seems safe to say that they always
exist under mingw, so just remove them and assume they're set exactly when on
mingw (with msvc, we use `pragma comment` instead of linking these via flags).

llvm-svn: 328992
diff --git a/llvm/lib/Support/Windows/Process.inc b/llvm/lib/Support/Windows/Process.inc
index 3fe9f89..06b32ea 100644
--- a/llvm/lib/Support/Windows/Process.inc
+++ b/llvm/lib/Support/Windows/Process.inc
@@ -24,14 +24,7 @@
 #include <psapi.h>
 #include <shellapi.h>
 
-#ifdef __MINGW32__
- #if (HAVE_LIBPSAPI != 1)
-  #error "libpsapi.a should be present"
- #endif
- #if (HAVE_LIBSHELL32 != 1)
-  #error "libshell32.a should be present"
- #endif
-#else
+#if !defined(__MINGW32__)
  #pragma comment(lib, "psapi.lib")
  #pragma comment(lib, "shell32.lib")
 #endif