[gtkmm] DLLs with debugging symbols on win32

[Cedric Gustin <cedric gustin swing be>]

As requested by some win32 developers, I have uploaded new gtkmm-2.2.1 and 
libsigc++-1.2.4 binaries with debugging symbols included in the DLLs 
(compiler flags : -O2 -g). You can find them on my site

http://www.pcpm.ucl.ac.be/~gustin/win32_ports/

in the individual files section of the "gtkmm on win32" page.

Please note that I have NOT updated the DLLs in the installer (the DLLs are 
simply stripped down versions of their counterparts found in the lib 
packages) to keep the size of the installer as small as possible. Libsigc++ 
is still at version 1.2.3 in the installer but its DLL is fully compatible 
with the newest 1.2.4 available as an individual file.

If a developer really wants to use the installer while having DLLs with 
debugging symbols, the easiest way is to overwrite the DLLs in Common 
Files\Gtkmm\2.2 with the content of the newest individual "bin" files.

Hopefully, everything will be back in sync for the next release of gtkmm.

Cedric