add stdint.h shim, include limits for SIZE_MAX on Android

include/compat/stdint.h

@@ -0,0 +1,19 @@
+/*
+ * Public domain
+ * stdint.h compatibility shim
+ */
+
+#ifdef _MSC_VER
+#include <../include/stdint.h>
+#else
+#include_next <stdint.h>
+#endif
+
+#ifndef LIBCRYPTOCOMPAT_STDINT_H
+#define LIBCRYPTOCOMPAT_STDINT_H
+
+#ifndef SIZE_MAX
+#include <limits.h>
+#endif
+
+#endif