The current setting assumes that gnulib is only used by dirs immediately under the source root. Trying to build it two or more levels deep fails. Switch GNULIB_BUILDDIR to a relative GNULIB_PARENT_DIR so that it can be used to construct both the build & source paths.
This is an import of gnulib that is used by gdb and gdbserver. To send patches, follow the gdb patch submission instructions in ../gdb/CONTRIBUTE. For maintainers, see ../gdb/MAINTAINERS. See update-gnulib.sh for instructions on updating gnulib.