3rdparty: fix glslang build on newer MinGW

3rdparty/bgfx/3rdparty/glslang/glslang/MachineIndependent/SymbolTable.h

@@ -68,6 +68,7 @@
 #include "../Include/Common.h"
 #include "../Include/intermediate.h"
 #include "../Include/InfoSink.h"
+#include <cstdint>
 
 namespace glslang {