Update the notes that this is also used for Visual Studio 2015 support,
and correct the MSVC_VER_LONG for MSVC 2015, which is 14, not 2015.
Also add a note that this can be used for other projects that have
Visual Studio build support.
"Add" Visual Studio 2015 projects by what we did before: Copy the Visual
Studio 2010 project files and replace the items in there as needed, as
the formats of the 2010 and 2015 projects are largely the same.
Without this change, out-of-tree distcheck doesn't get very far.
Similarly, allow *.vcxproj, *.props to be in either the builddir or
the srcdir.
Finally, since I'm touching these lines anyway, eliminate some
useless uses of cat: "cat x | sed 's/foo/bar/' > y" is
equivalent to "sed 's/foo/bar/' < x > y".
Bug: https://bugzilla.gnome.org/show_bug.cgi?id=748176
Reviewed-by: Chun-wei Fan <fanchunwei@src.gnome.org>
Make use of pattern rules when generating the Visual Studio 2012/2013
Projects from the Visual Studio 2010 projects, which will help to clean up
the file and also avoid problems when running items like 'make -jN dist'.
As the Visual Studio 2012/2013 are only slightly different from the Visual
Studio 2010 projects, we can provide support for them by using scripts to
copy the Visual Studio 2010 projects, and update the specific parts as
necessary.
Thus, there would be little maintenance overhead for these as only the 2010
projects need to be kept up-to-date as a result. This might change when we
do get the stack working with WinRT/Metro, but that's going to be another
totally different issue.
