gcc: Force linking to libgcc_s_dw2-1.dll

.. by adding to specs:
*libgcc
--undefined=___deregister_frame_info
--undefined=___register_frame_info

These flags get added twice to the ld command line
 because of %G appearing twice in:
*link_gcc_c_sequence
%G %L %G
so this should be tidied up really.
gcc: Fix new patch, bump pkgrel
tcl: Don't pass -static-libgcc when building shared version

.. as that's clearly a dumb thing to do as it puts the same requirement on
all DLLs that are linked in.
tk+tktable: Don't pass -static-libgcc when building shared version

.. as that's clearly a dumb thing to do as it puts the same requirement on
all DLLs that are linked in. The real bug was 'fixed' by:

https://github.com/Alexpux/MINGW-packages/commit/abf850d0fe3a07eef11cbef78f727c8f58da8998

I put fixed in quotes as theres difference of opinion as to whether
some other method isn't more correct. Kai Tietz wondered if passing
-fasynchronous-unwind-tables would fix this problem, but it didn't.
todo: Update with some of my current issues
gdb: Add patch for 7.8.1
Add package for Qwt build by Qt5
Fix contributor name. Fix QWT version in .pri file.
Merge pull request #329 from IngoMaindorfer/master

Add support for QWT 6.1.1 and QT5
Introduce Emacs
Merge pull request #330 from Haroogan/master

Introduce Emacs
Add clang patch to fix fabs lowering
Merge pull request #331 from Sh4rK/clang-fabs-fix

Add clang patch to fix fabs lowering
clang: Fix sha256 sum of new patch ..

.. which unfortunately doesn't fix the bug it's meant
to solve
clang-svn: Refresh MinGW-w64 driver patch

.. it's now a git patch applied with git am.
emacs: Fix conflict with Ctags
Merge pull request #333 from Haroogan/master

emacs: Fix conflict with Ctags
winpthreads-git: Define __{de,}register_frame_info in fake libgcc_s
l-smash: Update to 2.3.0
Merge pull request #334 from nak5124/l-smash

l-smash: Update to 2.3.0