[Ada] Remove Unknown_ functions

[Ada] Remove Unknown_ functions

gcc/ada/

	* einfo-utils.ads, einfo-utils.adb (Unknown_Alignment,
	Unknown_Component_Bit_Offset, Unknown_Component_Size,
	Unknown_Esize, Unknown_Normalized_First_Bit,
	Unknown_Normalized_Position, Unknown_Normalized_Position_Max,
	Unknown_RM_Size): Remove these functions.
	* exp_pakd.adb, exp_util.adb, fe.h, freeze.adb, layout.adb,
	repinfo.adb, sem_ch13.adb, sem_ch3.adb, sem_util.adb: Remove
	calls to these functions; do "not Known_..." instead.
	* gcc-interface/decl.c, gcc-interface/trans.c
	(Unknown_Alignment, Unknown_Component_Size, Unknown_Esize,
	Unknown_RM_Size): Remove calls to these functions; do
	"!Known_..." instead.