[Ada] GNAT-LLVM unnesting issues in elaboration code

[Ada] GNAT-LLVM unnesting issues in elaboration code

gcc/ada/

	* exp_ch7.adb (Check_Unnesting_In_Decls_Or_Stmts): In the case
	of an if-statement, call Unnest_If_Statement to determine
	whether there are nested subprograms in any of the statement
	lists of the "if" parts that require a wrapping procedure to
	handle possible up-level refeferences.
	(Unnest_Block): Call Check_Unnesting_In_Handlers to do unnesting
	of subprograms in exception handlers of the block statement.
	(Unnest_If_Statement): New procedure to traverse the parts of an
	if-statement and create wrapper procedures as needed to
	encapsulate nested subprograms that may make up-level
	references.
	(Check_Stmts_For_Subp_Unnesting): New support procedure in
	Unnest_If_Statement to traverse a statement list looking for
	top-level subprogram bodies that require wrapping inside a
	procedure (via Unnest_Statement_List) as well as possibly having
	other statements (block, loop, if) that may themselves require
	an unnesting transformation (via
	Check_Unnesting_In_Decls_Or_Stmts).
	(Unnest_Statement_List): New support procedure to traverse the
	statements of a statement list that contains subprogram bodies
	at the top level and replace the statement list with a wrapper
	procedure body encapsulating the statements and a call to the
	procedure.