Move source for Emacs on MS Windows FAQ here from Emacs webpages repository

Move source for Emacs on MS Windows FAQ here from Emacs webpages repository

* Makefile.in (mostlyclean, clean, distclean, bootstrap-clean)
(maintainer-clean, check-declare): Remove pointless subshells.
Check cd return value.

* configure.ac (DOCMISC_DVI_W32, DOCMISC_HTML_W32, DOCMISC_INFO_W32)
(DOCMISC_PDF_W32, DOCMISC_PS_W32): New output variables.
* Makefile.in (check-info-dir): Ignore efaq-w32.

* admin/admin.el (manual-misc-manuals): Use INFO_COMMON rather than
INFO_TARGETS.

* doc/misc/efaq-w32.texi: Move here from the web-pages repository.

* doc/misc/Makefile.in (DOCMISC_DVI_W32, DOCMISC_HTML_W32, DOCMISC_INFO_W32)
(DOCMISC_PDF_W32, DOCMISC_PS_W32): New configure output variables.
(INFO_COMMON, INFO_INSTALL): New derivations of INFO_TARGETS.
(DVI_TARGETS, HTML_TARGETS, PDF_TARGETS, PS_TARGETS):
Add DOCMISC_*_W32 variables.
(echo-info): Use INFO_INSTALL rather than INFO_TARGETS.
(efaq_w32_deps): New variable.
(efaq-w32, $(buildinfodir)/efaq-w32$(INFO_EXT), efaq-w32.dvi)
(efaq-w32.pdf, efaq-w32.html): New rules.
(clean): Remove efaq-w32 products.