mm/Makefile: Same change should be applied to mm/Makefile since the mm/ build is identical to the libc/ build.
libs/libnx/Makefile: Same change should be applied to libnx/Makefile since the mm/ build is identical to the libc/ build.
Author: chao.an <anchao@xiaomi.com>
libs/libc/Makefile: Correct the dependents path
Squashed commit of the following:
libs/libxx: Fix some confusing in naming. If the directory is called libxx, then the library must be libxx.a (unless perhaps LIBCXX is selected).
libs/: Fix paths in moved library directories.
libs: Brute force move of libc, libnx, and libxx to libs. Cannot yet build it in that configuration.