Add Ryan Sturgell to AUTHORS
Extract helper functions from main link loop.

This enables future changes which will re-scan archives for objects
(either grouped with -Wl,--start-group, -Wl,--end-group or some new
emcc specific flag).

This is mostly moving lines around and adding some comments. The only
functional change is that if you specify the same archive multiple times
(a workaround for the lack of grouping flags), we will now only extract
it once instead of multiple times. But it will still be scanned multiple
times.
Track original flag positions in emcc.

Source files, libs, and linker flags all need to be separately
processed.  This allows them to be correctly shuffled back together for
further link processing.
Add support for archive groups.

emcc now understands -Wl,--start-group, -Wl,--end-group to group static
libraries. Static libraries in a group need not be specified in
dependent to dependency order and can have circular dependencies.
Archive groups code review changes.
Merge branch 'archive_groups' of github.com:rsturgell/emscripten into incoming

Conflicts:
	AUTHORS