[Ada] Spurious warning on object declaration with address clause

[Ada] Spurious warning on object declaration with address clause

The compiler warns on an object declaration with default initialization
and an address clause, to indicate that the overlay implied by the address
clause might affect a value elsewhere. The warning is suppressed if the type
carries the Suppress_Initialization aspect. With this patch the compiler
also inhibits the warning if the aspect is specified for the object itself.

2018-05-21  Ed Schonberg  <schonberg@adacore.com>

gcc/ada/

	* freeze.adb (Warn_Overlay): Do not emit a wawrning on an object
	declaration with an explicit address clause and a type with default
	initialization, if the declaration carries an aspect
	Suppress_Initialization.

gcc/testsuite/

	* gnat.dg/suppress_initialization.adb,
	gnat.dg/suppress_initialization_pkg.ads: New testcase.

From-SVN: r260471