Squashed commit of the following:
Correct some additional compile-related issues.
Move include/nuttx/binfmt/builtin.h to include/nuttx/lib/builtin.h. Move apps/builtin/lib_builtin_forindex.c to libs/libc/builtin/lib_builtin_forindex.c.
Move binfmt/libbuiltin to libs/libc/builtin. There are calls made directly from apps/nshlib into this logic and hence, must be part of a library that can be shared between the OS and applications.
Squashed commit of the following:
Last minute clean-up
libs/libc/grp/lib_find_grpfile.c: Fix some problems found in testing.
libs/libc/pwd: Finishes off implementation using /etc/passwd.
libs/libc/grp: Finishes off implementation using /etc/group.
libs/libc/pwd/lib_find_pwdfile.c: Add logic to look up user information in /etc/passwd file, if available.
libs/libc/grp/lib_find_grpfile.c: Add logic to look up group information in /etc/group file, if available.
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.
