This was done with the help of callcatcher [1]. Only functions which
are statically known to be unused are removed.
Some unused functions are not removed yet, because they might be needed
in the near future (such as open_output_stream for the encode branch).
There is one user visible change: the --subcc option did nothing, and is
removed with this commit.
[1] http://www.skynet.ie/~caolan/Packages/callcatcher.html
Some of the code, especially the dshow and windows codec loader parts,
are extremely hacky and likely full of bugs. The goal is merely getting
rid of warnings that could obscure more important warnings and actual
bugs, instead of fixing actual problems. This reduces the number of
warnings from over 500 to almost the same as when compiling on Linux.
Note that many problems stem from using the ancient wine-derived
windows headers. There are some differences to the "proper" windows
header. Changing the code to compile with the proper headers would be
too much trouble, and it still has to work on Unix.
Some of the changes might actually break compilation on legacy MinGW,
but we don't support that anymore. Always use MinGW-w64, even when
compiling to 32 bit.
Fixes some warnings in the win32 loader code on Linux too.
There is no reason to use manual language list splitting when an
automatic split function is already available.
Some types change from "unsigned char" to "char", but this shouldn't
cause issues since [as]lang settings are unlikely to have characters
above 127.