Kernel/LibC: Implement unlinkat

userspace/libraries/LibC/include/sys/syscall.h

@@ -56,7 +56,7 @@ __BEGIN_DECLS
 	O(SYS_POWEROFF,			poweroff)		\
 	O(SYS_FCHMODAT,			fchmodat)		\
 	O(SYS_CREATE_DIR,		create_dir)		\
-	O(SYS_UNLINK,			unlink) 		\
+	O(SYS_UNLINKAT,			unlinkat) 		\
 	O(SYS_READLINKAT,		readlinkat)		\
 	O(SYS_MSYNC,			msync)			\
 	O(SYS_PREAD,			pread)			\

userspace/libraries/LibC/unistd.cpp

@@ -518,12 +518,17 @@ int fdatasync(int fildes)
 
 int unlink(const char* path)
 {
-	return syscall(SYS_UNLINK, path);
+	return unlinkat(AT_FDCWD, path, 0);
+}
+
+int unlinkat(int fd, const char* path, int flag)
+{
+	return syscall(SYS_UNLINKAT, fd, path, flag);
 }
 
 int rmdir(const char* path)
 {
-	return syscall(SYS_UNLINK, path);
+	return unlinkat(AT_FDCWD, path, AT_REMOVEDIR);
 }
 
 char* optarg = nullptr;