Clean up everything and add lots of new functions

I hope everything here is okay. I fixed some bugs in existing functions (mostly wrong prototypes or off-by-one errors) and formatted everything to a consistent style. If you'd like me to adjust the style, that's no problem. It wasn't very consistent to start with (within the code, and compared to the documentation).

I added specific notes you may want to comment on to some of the commit messages.

Major features:

• Pass correct argv[0] in loader
• Intercept readlink("/proc/self/exe") to allow re-exec
• Add almost all reasonable-to-implement functions in LSB 5.0.0 core generic libc. Remaining functions are:
  • Impossible-to-implement: sigreturn
  • Not useful: reentrant random (*rand48_r, etc.), argz, envz, pmap, rpc (clnt_, svc, xdr*), bindresvport
  • Got tired of it: checked wchar
• Add additional functions used by android and its NDK tools (clang, cmake, lldb, ninja, etc.).

At this point, I am able to run Android Studio with the bundled prebuilt JDK, and compile, install, and run an android application (including one with native libraries) on a real device, with only a few minor issues:

• must export LD_LIBRARY_PATH=/opt/android-studio/jre/jre/lib/amd64/server because musl and glibc interpret the variable differently with regards to dlopen. This is something that has to be patched in musl builds of openjdk, so it's not a gcompat issue.
• ld.bfd fails to parse the argument --sysroot=/path, but can parse --sysroot /path. So there's some difference with getopt_long_only (or getopt in general). May be a bug, may be just an API difference. May be it can be patched up.
• LLDB fails to connect to the android phone for native debugging -- I haven't tried it on glibc yet, so it may not be a gcompat issue at all (may be a phone or the app issue).

I'd be happy to send some documentation later.