build: fix more example extraction issues.

build: fix more example extraction issues.

	* Makefile.am (dist_TESTS): New.
	(TESTS, EXTRA_DIST): Run and ship them.
	* examples/calc++/local.mk: examples/calc++/calc++.stamp no longer
        exists, don't try to ship it.
	(.yy.stamp): New recipe.
	Use it.
	* examples/calc++/local.mk, examples/mfcalc/local.mk,
	* examples/rpcalc/local.mk:
	Don't ship the sources.
	Adjust the CPPFLAGS: there is nothing left in srcdir.
	(MAINTAINERCLEANFILES): Remove, now we are in builddir.
	(TESTS): Rename as...
	(dist_TESTS): this.