[Ada] Wrong handling of address clause for limited record type

[Ada] Wrong handling of address clause for limited record type

2018-09-26  Eric Botcazou  <ebotcazou@adacore.com>

gcc/ada/

	* gcc-interface/decl.c (gnat_to_gnu_entity) <E_Variable>: Adjust
	code retrieving the address when a clause has already been
	processed.
	* gcc-interface/trans.c (gnat_to_gnu)
	<N_Attribute_Definition_Clause>: For an object with a Freeze
	node, build a meaningful expression.

gcc/testsuite/

	* gnat.dg/addr12.adb, gnat.dg/addr12_a.adb,
	gnat.dg/addr12_a.ads, gnat.dg/addr12_b.adb,
	gnat.dg/addr12_b.ads, gnat.dg/addr12_c.ads: New testcase.

From-SVN: r264606