If an output section is skipped because of a constraint, then skip it
when generating the link map output (-M) too

ok kettenis@

Port over binutils fix for PR ld/3111.

This greatly speeds up up linking of object files that contain
lots of dwarf2 symbols by caching symbol tables.

Original patch before binutils was switched to GPLv3 from:
https://sourceware.org/ml/binutils/2006-08/msg00334.html

Aaron Miller made us aware of that diff and adapted it to our
in-tree binutils. Many thanks!

Ports build testing on amd64 by krw@
ok deraadt@ krw@

Unbreak binutils on sparc64, hppa (and probably some others).
Jumbo merges are NOT WELCOME. They have to be seperated out and tested.

Introduce -Bsymbolic-functions and related flags. Taken from two
post-binutils 2.17 but pre-GPLv3 commits.
miod@ says now is the time to get this in.

branches: 1.1.1;
Initial revision