[patch] Emit aliases for more constructors (V2)

[Rafael Espíndola]

> Since you've got it setup, have you run this against the GDB 7.5 test suite?

Ah, thanks. I had checked just the case that broke before. It is a
alias from derived to base. We don't produce such an alias anymore
since it would also hit the "same comdat rule". I will add an explicit
test of that.

Running the gdb tests now I got:

# of expected passes 4737
# of unexpected successes 1
# of expected failures 23
# of unknown successes 2
# of known failures 7
# of untested testcases 6
# of unsupported tests 4

both with and without the patch.

Cheers,
Rafael