[Ada] Annotate GNAT.Sockets with No_Return aspects

Opportunity for extra annotations spotted while fixing detection of
unreachable code that follows calls to procedures annotated with
No_Return.

gcc/ada/

	* libgnat/g-socket.adb (Raise_Host_Error): Add No_Return aspect.
	(Raise_GAI_Error): Likewise.
	* libgnat/g-socket.ads (Raise_Socket_Error): Likewise.
2 files changed