sched/clock: Move the implementation of clock() from libs/libc/time to sched/clock. This is necessary because it calls the (now) internal OS function clock_systimer. clock() is now accessed only via a system call in certain configuratins.
libs/libc/wqueue: Replace calls to clock_systimer() with calls to the equivalent clock().
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.
Alan Carvalho de Assis