[Ada] Forbids use of Compile_Time_(Error|Warning) as configuration pragma

[Ada] Forbids use of Compile_Time_(Error|Warning) as configuration pragma

gcc/ada/

	* sem_prag.adb (Analyze_Pragma): Forbid use of
	Compile_Time_(Error|Warning) as configuration pragma.
	* doc/gnat_ugn/the_gnat_compilation_model.rst:
	Compile_Time_(Error|Warning) and Compiler_Unit(_Warning) are not
	configuration pragmas and shall not be listed as such.  The
	following pragmas are either obsolete or undocumented:
	No_Run_Time, Propagate_Exceptions, Rational, Ravenscar,
	Restricted_Run_Time, Short_Descriptors, Universal_Data.  Fix
	some typos (notably on Restriction_Warnings).
	* doc/gnat_rm/implementation_defined_pragmas.rst: Move
	Rename_Pragma documentation to alphabetical order.
	* gnat_rm.texi, gnat_ugn.texi: Regenerate.