PR libstdc++/48760
	Implement list-initialization of _Complex.
	* decl.c (reshape_init_r): Allow {real,imag} for _Complex.
	(check_initializer): Likewise.
	* call.c (build_complex_conv): New.
	(implicit_conversion): Call it.
	(convert_like_real): Handle it.
	* typeck2.c (check_narrowing): Handle it.

From-SVN: r173058