Optional libraries

[Nikolay Kudryavtsev]

Hello.

I'm currently trying to make sense of the possible optional libraries 
that are used on Windows.

Can someone help me document them?

Here's a list I lifted from emacs-w64 project, with some commentaries added.

libbwinpthread-*.dll ; msys2 built emacs does not work without it? Does 
not exist in official builds...
libdbus-*.dll ; is there a single legitimate usecase for dbus on windows?
;; Image support
libpng*.dll ; png images
libtiff-*.dll
libtiffxx-*.dll ; tiff images
libjpeg-*.dll ; jpeg images
libgif-*.dll ; gif images
libXpm-noX*.dll ; xpm images
;; rsvg dependencies
libglib-*.dll
libcairo-*.dll
libcroco-*.dll
libpango-*.dll
libpangocairo-*.dll
libpangoft*.dll
libpangowin32-*.dll
librsvg-*.dll ; svg images
;; Gnutls dependencies
libffi-*.dll ; only needed for msys2-based builds
libgmp-*.dll
libgnutls-*.dll
ibgnutls-openssl-*.dll ; only in Eli's gnutls build
libgnutlsxx-*.dll ; only in msys2, same library as the previous one, 
with a different name?
libhogweed-*.dll
libiconv-*.dll
libidn-*.dll ; only needed for msys2-based builds
libintl-*.dll
libnettle-*.dll
libp11-kit-*.dll
libtasn1-*.dll
zlib*.dll
;; Unknown
libgomp-*.dll
libgcc_s_seh-*.dll
libgobject-*.dll
libgdk_pixbuf-*.dll
libgio-*.dll
libgmodule-*.dll
libxml2-*.dll
libfontconfig-*.dll
libfreetype-*.dll
libpixman-*.dll
liblzma-*.dll
libexpat-*.dll
libharfbuzz-*.dll
libbz2-*.dll
libjbig-*.dll


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Best Regards,
Nikolay Kudryavtsev