This patch adds testcase for base-in-references bug that was recently fixed.
I've verified that the new testcase fails with my patches reverted, and passes
when they are put back. OK?

- Volodya

	Test for base in references.
	* gdb.mi/mi-var-cp.cc: Add test code.
	* gdb.mi/mi-var-cp.exp: Test for bases in references.
	* gdb.mi/mi-watch.exp: Adjust to mi_runto changes.
	* gdb.mi/mi2-watch.exp: Likewise.
	* lib/mi-support.exp (mi_runto): Use temporary breakpoint.
	(mi_list_varobj_children): New function.