[Ada] Transient scope cleanup

[Ada] Transient scope cleanup

gcc/ada/

	* comperr.adb (Compiler_Abort): Call Sinput.Unlock, because if
	this is called late, then Source_Dump would crash otherwise.
	* debug.adb: Correct documentation of the -gnatd.9 switch.
	* exp_ch4.adb (Expand_Allocator_Expression): Add a comment.
	* exp_ch6.adb: Minor comment fixes.  Add assertion.
	* exp_ch6.ads (Is_Build_In_Place_Result_Type): Correct comment.
	* exp_ch7.adb, checks.ads: Minor comment fixes.