Dynamic linker committed!

[Rich Felker <dalias@aerifal.cx>]

Greetings,

The dynamic linker has been committed and is ready for testing. To use
it, libc.so needs to be installed somewhere convenient and the
-Wl,-dynamic-linker option needs to be passed to glibc to tell it
which dynamic linker to use. The eventual name I intend to use (short
of better suggestions) is /lib/ld-musl-$ARCH.so.1 where $ARCH is i386,
x86_64, etc. The idea of including $ARCH is that if a system can
support multiple archs' binaries (e.g. i386 and x86_64) no additional
special-casing of the dynamic linker name is required.

At present, the library search path is hard coded as
/lib:/usr/local/lib:/usr/lib. Obviously this only works if you have a
musl-based system rather than having glibc stuff in those paths, so
until I add configurability, you might want to edit the path in
src/ldso/dynamic.c manually when building.

Also note that there is no support for LD_* env vars, which in turn
means no support for the "ldd" program. Some support may be added
later.

My plan is to fix up some of these issues over the next week and make
an experimental release for more widespread testing, then move on to
the 0.8.x series with official dynamic linking support including the
addition of dlopen/dlsym functionality. This should in turn make it
possible to use much of the important previously-unusable software
like python, X.org, etc. with musl.

Rich