feat(userspace/libc): add <getopt.h> header

Signed-off-by: EnderIce2 <enderice2@protonmail.com>

Userspace/libc/include/getopt.h

@@ -0,0 +1,28 @@
+/*
+	This file is part of Fennix C Library.
+
+	Fennix C Library is free software: you can redistribute it and/or
+	modify it under the terms of the GNU General Public License as
+	published by the Free Software Foundation, either version 3 of
+	the License, or (at your option) any later version.
+
+	Fennix C Library is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with Fennix C Library. If not, see <https://www.gnu.org/licenses/>.
+*/
+
+#ifndef _GETOPT_H
+#define _GETOPT_H
+
+#include <unistd.h>
+
+extern int opterr, optind, optopt;
+extern char *optarg;
+
+int getopt(int argc, char *const argv[], const char *optstring);
+
+#endif // _GETOPT_H