Clean up the clean rules of the documentation

Most things should be cleaned by "make clean", except the parts that are
shipped in the tarball.  These rules had gotten a bit out of whack after
the various restructurings of the documentation build rules.

doc/src/sgml/Makefile

@@ -2,7 +2,7 @@
 #
 # PostgreSQL documentation makefile
 #
-# $PostgreSQL: pgsql/doc/src/sgml/Makefile,v 1.132 2009/10/06 00:54:26 alvherre Exp $
+# $PostgreSQL: pgsql/doc/src/sgml/Makefile,v 1.133 2009/10/06 20:00:44 petere Exp $
 #
 #----------------------------------------------------------------------------
 
@@ -354,21 +354,19 @@ endif # sqlmansectnum != 7
 .SECONDARY: %-A4.tex-ps %-US.tex-ps %-A4.tex-pdf %-US.tex-pdf
 
 clean:
-	rm -f postgres.xml $(GENERATED_SGML) HTML.index
-	rm -f INSTALL.html HISTORY.html regress_README.html
-	rm -f $(addprefix $(srcdir)/,*.tex-ps *.tex-pdf *.dvi *.aux *.log *.out *.fot)
-
-distclean: clean
 # text --- these are shipped, but not in this directory
-	rm -f $(addprefix $(srcdir)/,INSTALL HISTORY regress_README)
+	rm -f INSTALL HISTORY regress_README
+	rm -f INSTALL.html HISTORY.html regress_README.html
 # print
-	rm -f $(addprefix $(srcdir)/,*.rtf *.ps *.pdf)
+	rm -f *.rtf *.tex-ps *.tex-pdf *.dvi *.aux *.log *.ps *.pdf *.out *.fot
 # index
-	rm -f $(addprefix $(srcdir)/,HTML.index $(GENERATED_SGML))
+	rm -f HTML.index $(GENERATED_SGML)
 # XSLT
-	rm -f $(addprefix $(srcdir)/,htmlhelp.hhp toc.hhc index.hhk *.fo)
+	rm -f postgres.xml htmlhelp.hhp toc.hhc index.hhk *.fo
 # Texinfo
-	rm -f $(addprefix $(srcdir)/,*.texixml *.texi *.info db2texi.refs)
+	rm -f *.texixml *.texi *.info db2texi.refs
+
+distclean: clean
 
 maintainer-clean: distclean
 # HTML