bug in makefiles: phony targets

[Taylor R Campbell]

The makefiles don't identify the phony targets.  This could have
confusing consequences for everyone if any files were added to the
source tree that happen to share names with the phony targets, and it
already does have confusing consequences for anyone trying to build
rxvt-unicode on case-insensitive file systems such as Mac OS X's HFS+,
because there is a file called `INSTALL' in the top-level directory
that inhibits the rule for the `install' target from triggering.

Here's what I think each makefile needs, based on a cursory
examination of them:

# Makefile.in

.PHONY: first_rule dummy all allbin alldoc tags clean distclean realclean
.PHONY: install rxvt check Makefiles cleandir distclean-local distdir tar.gz
.PHONY: tar.bz2 dist

# doc/Makefile.in

.PHONY: first_rule dummy all tags allbin alldoc clean distclean realclean
.PHONY: cleandir install distdepend

# src/Makefile.in

.PHONY: first_rule dummy all allbin alldoc clean distclean realclean cleandir
.PHONY: install-perl install-bin install depend