FindGTK2: Add GTK2_DEFINITIONS variable

According to https://wiki.gnome.org/gtkmm/MSWindows on MSVC the /vd2
flag should be passed to the compiler in order to use gtkmm
KWSys 2013-07-01 (f6c4c247)

Extract upstream KWSys using the following shell commands.

$ git archive --prefix=upstream-kwsys/ f6c4c247 | tar x
$ git shortlog --no-merges --abbrev=8 --format='%h %s' 3d1d4e7c..f6c4c247
Sean McBride (1):
      f6c4c247 RegularExpression: Remove 'register' storage specifier

Change-Id: I755712879ab86fa163f5fce684fff2f0ecd8ab99
Merge branch 'upstream-kwsys' into update-kwsys
Fortran: Use explicit type in Fortran 90 check

In CMakeTestFortranCompiler we build a test program using a Fortran 90
construct to check whether the compiler supports the language.  Some
compilers have options to require explicit variable types.  Fix the test
program to use an explicit variable type so it passes under such a
configuration.

Suggested-by: Neil Carlson <neil.n.carlson@gmail.com>
Merge topic 'FindGTK2vd2'

60e4555 FindGTK2: Add GTK2_DEFINITIONS variable
Merge topic 'update-kwsys'

c314da0 Merge branch 'upstream-kwsys' into update-kwsys
2e3c935 KWSys 2013-07-01 (f6c4c247)
Merge topic 'Fortran-explicit-types'

7b5bc2c Fortran: Use explicit type in Fortran 90 check