Sorry, the last commit added a generated file instead of the
template.
G-I has been updated to not require a Windows GCC installation
anymore to generate the .gir files, so update the NMake Makefiles
that are used for this purpose.
As a result, it is no longer necessary to define time_t for the .gir
generation as we are on the same compiler throughout the process.
Make the Visual C++-related build files contain the actual GTK+ version, by
generating them during the configure stage and dist'ing them in the release
tarballs. This is especially important for builds of introspection files,
as one may need to look at the release version of GTK+ in those files.
