Updating libc comparison

[Rich Felker <dalias@aerifal.cx>]

I'd like to think about doing some serious updates to the libc
comparison soon. Some things that have come up which we should add:

Rows:
- Security features: relro and fortify, crypt hashes, maybe others
- Source size in kloc: musl=75, uclibc=333, glibc=1188
- Number of files/kloc that are arch-specific (aka porting effort)
- Dynamic linking timings

Columns:
- Bionic
- klibc
- Replace eglibc with glibc (eglibc is being discontinued)

In addition, the uClibc and glibc tests should be re-run with the
latest versions (I don't think dietlibc has a new version), and the
specific version and parameters used should be documented. Dietlibc's
arch support is also reportedly over-stated; this should be checked.

Of these, the biggest project (and the one I've been reluctant to do
myself because setting up a dev environment seems like such a pain) is
testing Bionic. If anyone has advice on how to make this easy (i.e.
avoiding the Android build system) or wants to do it for me, please
let me know! :-)

Rich