changed the WIN32 macro in microprofileui (#2528)

I changed the macro in microprofileui.h from WIN32 to _WIN32 so that it
would correctly dectect that its being compiled on a windows platform

externals/microprofile/microprofileui.h

@@ -1231,7 +1231,7 @@ void MicroProfileDrawDetailedBars(uint32_t nWidth, uint32_t nHeight, int nBaseY,
                 char ThreadName[MicroProfileThreadLog::THREAD_MAX_LEN + 16];
                 const char* cLocal = MicroProfileIsLocalThread(nThreadId) ? "*": " ";
 
-#if defined(WIN32)
+#if defined(_WIN32)
                 // nThreadId is 32-bit on Windows
                 int nStrLen = snprintf(ThreadName, sizeof(ThreadName)-1, "%04x: %s%s", nThreadId, cLocal, i < nNumThreadsBase ? &S.Pool[i]->ThreadName[0] : MICROPROFILE_THREAD_NAME_FROM_ID(nThreadId) );
 #else