varasm.c (output_constant_def_contents): Use ASM_DECLARE_CONSTANT_NAME if defined.

varasm.c (output_constant_def_contents): Use ASM_DECLARE_CONSTANT_NAME if defined.

	* varasm.c (output_constant_def_contents): Use
	ASM_DECLARE_CONSTANT_NAME if defined.
	* doc/tm.texi (Label Output): Document ASM_DECLARE_CONSTANT_NAME.
	* config/darwin.h (ASM_DECLARE_OBJECT_NAME): Ensure zero-sized
	objects get at least one byte to prevent assembler problems.
	(ASM_DECLARE_CONSTANT_NAME): New.

Index: testsuite/ChangeLog
	* gcc.c-torture/compile/zero-strct-2.c: New test.

From-SVN: r69842