[libcxx] [test] Fix the get_temp_file_name() function for mingw

[mstorsjo]

Summary

Add the missing includes for getting the defines and functions used in the mingw version of get_temp_file_name().

This fixes 31 tests when built in a mingw configuration.

Also remove a redundant ifdef; _WIN32 is defined in mingw targets too.

[curdeius]

libcxx/test/support/platform_support.h

60

Would defining VC_EXTRALEAN as well be beneficial and possible?

[mstorsjo]

libcxx/test/support/platform_support.h

59–60

The defined(__MINGW32__) here is redundant; _WIN32 is defined in mingw configurations too, will amend the patch to simplify that while touching these lines.

60

That one only seems to have an effect on ATL/MFC headers (I think), which we don't use here. (I hadn't ever heard of that one before actually.) On a MSVC 2019 installation (without ATL/MFC) I get no hits in the headers when grepping for that.

[mstorsjo]

Removed the superfluous defined(__MINGW32__).

[mstorsjo]

Bump

[curdeius]

LGTM.

[mstorsjo]

Ping for second approval

[• Quuxplusone]

I don't know much about Windows, but it seems like you know what you're doing. :)

libcxx/test/support/platform_support.h

 #   define LOCALE_zh_CN_UTF_8     "zh_CN.UTF-8"
 #endif
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <codecvt>
 #include <locale>
 #include <string>
-#if defined(_WIN32) || defined(__MINGW32__)
+#if defined(_WIN32)
+#   define WIN32_LEAN_AND_MEAN // Reduce overhead of including windows.h
 #   include <io.h> // _mktemp_s
+#   include <windows.h> // MAX_PATH, GetTempPath, GetTempFileName
 #else
 #   include <unistd.h> // close
 #endif
 
 #if defined(_NEWLIB_VERSION) && defined(__STRICT_ANSI__)
 // Newlib provides this, but in the header it's under __STRICT_ANSI__
 extern "C" {
   int mkstemp(char*);