Update mpc-hc_setup.iss.

* simplify a preprocessor check
* rename a function
* use a wildcard for the translation dlls
* reindent
installer: remove unneeded strings from Inno Setup's language files
custom_messages.iss: update copyright year
checkyear.sh: add .iss files in the files to check
Initialize variables in the constructor.
Cppcheck fixes:

* reduce variable scope
* remove unneeded variable assignments
update Little CMS to v2.5 (git a4847b0)
Fix camelcase word "Charset".