user: implement mlibc as the libc, finally.

It's finally done..

Signed-off-by: kaguya <vpshinomiya@protonmail.com>

ext2_root/usr/include/bits/glibc/glibc_signal.h

@@ -0,0 +1,24 @@
+#ifndef MLIBC_GLIBC_SIGNAL_H
+#define MLIBC_GLIBC_SIGNAL_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef __MLIBC_ABI_ONLY
+
+int tgkill(int __tgid, int __tid, int __sig);
+
+#if defined(_GNU_SOURCE)
+
+typedef void (*sighandler_t)(int __signo);
+
+#endif
+
+#endif /* !__MLIBC_ABI_ONLY */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* MLIBC_GLIBC_SIGNAL_H */