Build libpakrd with cmake instead of using it as prebuilt library

intern/pakrd/include/io.h

@@ -0,0 +1,25 @@
+#ifndef IO_H
+#define IO_H
+
+#include "SDL_rwops.h"
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+#include "aliases.h"
+#include <linux/limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+
+#define STREQ(S1, S2) (strcmp(S1, S2) == 0)
+#define STRNEQ(S1, S2, COUNT) (strncmp(S1, S2, COUNT) == 0)
+
+u64 get_file_length(SDL_RWops *io);
+void read_entire_file(void *dst, SDL_RWops *io);
+
+#ifdef __cplusplus
+}
+#endif // __cplusplus
+
+#endif // !IO_H