feat: implement utime libc function, SYS_UTIME syscall, filesystem support (ext2 only)

programs/include/libc/utime.h

@@ -14,8 +14,7 @@ struct utimbuf {
     time_t modtime;
 };
 
-/* Accepted for POSIX compatibility; the Montauk VFS does not support
-   setting file times. */
+/* Set access and modification times. Currently supported on ext2. */
 int utime(const char *path, const struct utimbuf *times);
 
 #ifdef __cplusplus