more things are done by configure: checks for bool, whether overloading based

more things are done by configure: checks for bool, whether overloading based
on size_t/int works or not (for wxString), the type of 3rd argument to
getsockaddr, absence of libXpm is not fatal (not tested), whether strings.h
exists

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@1914 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775