Cygwin: Do not build testVisualStudioSlnParser

When CMake is built with a CMake version older than 2.8.4 then
WIN32 will be defined on Cygwin.  Build the test only under the
same conditions as we build what it tests.
Merge topic 'msbuild-targets-in-subdirs' into next

02bfd97 Cygwin: Do not build testVisualStudioSlnParser