build: fix distcheck

Now that distcheck no longer fails (see previous commit), let's
address the shortcomings.

* Makefile.am (CLEANDIRS, clean-local): New.
* doc/local.mk, examples/calc++/local.mk, examples/local.mk,
* examples/mfcalc/local.mk, examples/rpcalc/local.mk,
* src/local.mk
(CLEANDIRS): Get rid of Apple's *.dSYM directories.
(CLEANFILES): Get rid of *.output files.
* examples/variant-11.yy, examples/variant.yy: Don't generate
any of the auxiliary files (location.hh and the like).

src/local.mk

@@ -116,6 +116,7 @@ bin_SCRIPTS = src/yacc
 endif
 EXTRA_SCRIPTS = src/yacc
 MOSTLYCLEANFILES += src/yacc
+CLEANDIRS += %D%/*.dSYM
 
 src/yacc:
 	$(AM_V_GEN)rm -f $@ $@.tmp