re PR lto/51774 (FAIL: gcc.dg/lto/trans-mem-* c_lto_trans-mem-1_0.o-c_lto_trans-mem-1_1.o link, -flto -fgnu-tm)

	PR lto/51774
	* lto-lang.c (handle_returns_twice_attribute): New function.
	(lto_attribute_table): Add returns_twice attribute.

From-SVN: r182959