Work around "missing" LLONG_MAX &c in MinGW strict ANSI mode.

Definitions of non-standard LLONG_MAX, LLONG_MIN and ULLONG_MAX constants are
excluded from MinGW limits.h when compiling in "strict ANSI" mode, so define
them ourselves.

src/propgrid/props.cpp

@@ -55,6 +55,14 @@
 #include "wx/numformatter.h"
 
 #include <float.h>
+#include <limits.h>
+
+// MinGW in strict ANSI mode doesn't define those in its limits.h.
+#if defined(wxNEEDS_STRICT_ANSI_WORKAROUNDS) && !defined(LLONG_MAX)
+    #define LLONG_MAX 9223372036854775807LL
+    #define LLONG_MIN (-LLONG_MAX - 1)
+    #define ULLONG_MAX (2ULL*LLONG_MAX + 1)
+#endif
 
 // -----------------------------------------------------------------------
 // wxStringProperty