MSVC Builds: Fix Missed Headers for "Install"

There were some more m4-generated headers that need to be installed.  Make
up for that.

	* MSVC_Net2008/glibmm-install.vsprops:
	* MSVC_Net2010/glibmm-install.props: "Install" the generated
	  headers indicated by glibmm_files_h_m4.