#2201 Fix 32-bit MSVC compiler error due to unknown command #warning (#2202)

httplib.h

@@ -16,8 +16,13 @@
  */
 
 #if defined(_WIN32) && !defined(_WIN64)
+#if defined(_MSC_VER)
+#pragma message(                                                               \
+    "cpp-httplib doesn't support 32-bit Windows. Please use a 64-bit compiler.")
+#else
 #warning                                                                       \
     "cpp-httplib doesn't support 32-bit Windows. Please use a 64-bit compiler."
+#endif
 #elif defined(__SIZEOF_POINTER__) && __SIZEOF_POINTER__ < 8
 #warning                                                                       \
     "cpp-httplib doesn't support 32-bit platforms. Please use a 64-bit compiler."