LibC: Implement getopt_long{,_only}

Few ports attempt to use this so lets add them :D

userspace/libraries/LibC/include/getopt.h

@@ -0,0 +1,27 @@
+#ifndef _GETOPT_H
+#define _GETOPT_H 1
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+#include <bits/getopt.h>
+
+struct option
+{
+	const char* name;
+	int has_arg;
+	int* flag;
+	int val;
+};
+
+#define no_argument 0
+#define required_argument 1
+#define optional_argument 2
+
+int getopt_long(int argc, char* argv[], const char* optstring, const struct option* longopts, int* longindex);
+int getopt_long_only(int argc, char* argv[], const char* optstring, const struct option* longopts, int* longindex);
+
+__END_DECLS
+
+#endif