Include sys/types.h for PIC32 port

On PIC32MZ, this is required to get `ntohl` and friends.

PUBLISHED_FROM=82ab532cd3757df6f79215f3eaca90cd87f6c965

mongoose.h

@@ -1432,6 +1432,8 @@ typedef struct stat cs_stat_t;
 #include <system_config.h>
 #include <system_definitions.h>
 
+#include <sys/types.h>
+
 typedef TCP_SOCKET sock_t;
 #define to64(x) strtoll(x, NULL, 10)