add: Android 9 support (#117)

This commit makes ReZygisk load Zygisk libraries directly, not utilizing memfd, as it doesn't exist in older versions of Android.

loader/src/include/files.hpp

@@ -2,6 +2,7 @@
 #include <functional>
 #include <string>
 #include <vector>
+#include <unistd.h>
 
 struct mount_info {
     unsigned int id;
@@ -26,6 +27,8 @@ void file_readline(const char *file, const std::function<bool(std::string_view)>
 
 std::vector<mount_info> parse_mount_info(const char *pid);
 
+int get_path_from_fd(int fd, char *buf, size_t size);
+
 using sFILE = std::unique_ptr<FILE, decltype(&fclose)>;
 using sDIR = std::unique_ptr<DIR, decltype(&closedir)>;
 sDIR make_dir(DIR *dp);