Add test name argument to get_valueof, get_integer_valueof and get_sizeof

Add test name argument to get_valueof, get_integer_valueof and get_sizeof

An optional parameter TEST has been added to get_hexadecimal_valueof in commit:

  https://sourceware.org/ml/gdb-patches/2016-06/msg00469.html

This patch adds a similar optional parameter to other related methods that
retrieve expression values: get_valueof, get_integer_valueof and get_sizeof.
Thus tests that evaluate same expression multiple times can provide custom
test names, ensuring that test names will be unique.

gdb/testsuite/ChangeLog:
2017-03-14  Anton Kolesov  <anton.kolesov@synopsys.com>

	* lib/gdb.exp (get_valueof, get_integer_valueof, get_sizeof):
	  Add optional 'test' parameter.