enable LARGEFILE64 aliases

these will NOT be used when compiling with -D_LARGEFILE64_SOURCE on
musl; instead, they exist in the hopes of eventually being able to run
some glibc-linked apps with musl sitting in place of glibc.

also remove the (apparently incorrect) fcntl alias.

src/fcntl/fcntl.c

@@ -16,5 +16,3 @@ int fcntl(int fd, int cmd, ...)
 	if (cmd == F_GETOWN) return __syscall(SYS_fcntl, fd, cmd, arg);
 	return syscall(SYS_fcntl, fd, cmd, arg);
 }
-
-LFS64(fcntl);

src/internal/libc.h

@@ -62,8 +62,7 @@ extern char **__environ;
 	extern __typeof(old) new __attribute__((weak, alias(#old)))
 
 #undef LFS64_2
-//#define LFS64_2(x, y) weak_alias(x, y)
-#define LFS64_2(x, y) extern __typeof(x) y
+#define LFS64_2(x, y) weak_alias(x, y)
 
 #undef LFS64
 #define LFS64(x) LFS64_2(x, x##64)