Fix several compiler errors for mingw-32

Change-Id: Ia1628a6130b6614f0471810d88e7a5e112276484

aom/aom_integer.h

@@ -61,6 +61,18 @@ typedef size_t uintptr_t;
 #include <inttypes.h>
 #endif
 
+#if !defined(INT8_MAX)
+#define INT8_MAX 127
+#endif
+
+#if !defined(INT32_MAX)
+#define INT32_MAX 2147483647i32
+#endif
+
+#if !defined(INT32_MIN)
+#define INT32_MIN (-2147483647i32 - 1)
+#endif
+
 #define NELEMENTS(x) (int)(sizeof(x) / sizeof(x[0]))
 
 #endif  // AOM_AOM_INTEGER_H_

test/txb_test.cc

@@ -17,6 +17,7 @@
 
 #include "./aom_config.h"
 #include "./av1_rtcd.h"
+#include "aom/aom_integer.h"
 #include "aom_ports/aom_timer.h"
 #include "aom_ports/mem.h"
 #include "av1/common/onyxc_int.h"