AutoFDO: Use filenames to resolve clashing symbol names

AutoFDO: Use filenames to resolve clashing symbol names

Signed-off-by: Dhruv Chawla <dhruvc@nvidia.com>
gcc/ChangeLog:

	* auto-profile.cc (string_table::~string_table): Update to free
	original_names_map_.
	(string_table::original_names_map_): New member.
	(string_table::clashing_names_map_): Likewise.
	(string_table::get_original_name): New function.
	(string_table::read): Figure out clashes while reading.
	(autofdo_source_profile::offline_external_functions): Call
	get_original_name.