lang/gcc-aux: Fix build for pure NetBSD/clang amd64 system

A new bootstrap was necesssary to allow gcc-aux to build on a NetBSD
system that has no gcc files on the system.  Other changes include:

* Remove support for NetBSD 5.99
* Remove defunct mirror site
* Restore action install stripped binaries (gcc bug fixed)
Fix build under Solaris (10?) by providing implementations of strcasestr(3)
and strsep(3) taken from NetBSD.
Fix build under Mac OS X.
Fixed broken checksum
Remove obsolete MirBSD workaround, fix build.
Update ruby-nokogiri to 1.5.11, fixing security problem of CVE-2013-6461.
This problem is in JRuby only, but JRuby exists in pkgsrc-wip.

=== 1.5.11 / 2013-12-14

* Bugfixes

  * (JRuby) Fix out of memory bug when certain invalid documents are parsed.
  * (JRuby) Fix regression of billion-laughs vulnerability. #586
Note update of textproc/ruby-nokogiri package to 1.5.11.
Update the COMMENTs for the firefox packages to include the upstream
version number, as suggested in PR 47418 a year ago. Also make sure
the localization packages claim they belong to the right corresponding
firefox packages, as a number of them were wrong.
lang/gcc-aux: Keep original bootstrap for NetBSD/i386

The last change to the Makefile was created months ago, and at the time
it was intended that new bootstraps would be made for both x86_64 and
i386 platforms.  The latter bootstrap was never created, so the previous
commit broke the build on i386.

Until a new bootstrap compiler is created, continue to use the old one.
It will continue to build on gcc-based NetBSD, but I do not expect it to
build on NetBSD-6.99/i386 with clang and no gcc libraries.
Update to 0.61

Changelog:
* backup-files is rewritten by bash now
* Many bugfixes
* Many cleanups
Updated devel/quilt to 0.61