Add description of environment variables

Write down the environment variables (and their descriptions) that can be
set in the environment prior to the invocation of the configure script.
Those will be shown when running "configure --help".
Notice about configure script ignoring CLI flags

The shipped configure script mimics those created by autotools, but it is
not one, so it seems sensible to warn users about that fact when running
"configure --help"
Import eglibc-2.18 nss_files
Rename s/files/altfiles and make standalone

This patch changes the prefixes of _nss_files_* functions to
_nss_altfiles_*, and neccessary modifications to make the module
buildable in a standalone fashion.

It also adds support for #define'ing ALTFILES_DATADIR to specify
a particular user info data files path instead of the /lib default.
Files neccessary for building, README, .gitignore

Adds build support files (configure, Makefile), a README.md file
and Git ignored file patterns (.gitignore).
Makefile: New "dist" target, creates tarballs
Do not create symlink on install

When using the "install" make target, do not symlink libnss_altfiles.so.2
to libnss_altfiles.so: glibc2 and eglibc will directly load the .2-suffixed
shared object without needing the symlink. The .so.1/.so suffixes would be
for supporting glibc1, but this NSS module is not expected to work with such
and older libc. Therefore, the symlink can just be dropped.
Support configurable alternate NSS module name

This makes it possible to pass --with-module-name=FOO to the "configure"
script, so a libnss_FOO.so.2 library is created. This effectively enables
to build modules with different names and data directories from the same
sources.
Fix linking building for 32-bit in a 64-bit host

Links the shared library using -nostdlib, which is safe because the
undefined symbols would be available later on when the shared library
is loaded as a plugin by the libc. Yet, -lpthread is kept to ensure
that the mutex will work as expected.

Also, -as-needed is passed to the linker to avoid including unneeded
dependencies in the ELF header of the shared library.
Add description of environment variables

Write down the environment variables (and their descriptions) that can be
set in the environment prior to the invocation of the configure script.
Those will be shown when running "configure --help".
Notice about configure script ignoring CLI flags

The shipped configure script mimics those created by autotools, but it is
not one, so it seems sensible to warn users about that fact when running
"configure --help"
Convenience script to download original eglibc files
Convenience script to download original eglibc files
Merge branch 'master' of https://github.com/aperezdc/nss-altfiles
Adapt download script to use svn export instead of viewcvs

This just makes me feel less icky.
Sync with 2.18
Merge branch 'v2.18' of https://github.com/aperezdc/nss-altfiles into tmp

Conflicts:
	Makefile
	compat.h
	dlfiles
	files-XXX.c
	files-parse.c
Define new ALTFILES_SYMBOL macros to replace CONCAT

The chaining of CONCAT macros was a bit ugly, this cleans up the changes
required to port files from glibc to altfiles.
Fix the Makefile's build dependencies for included sources.