Remove <memory> usages from abg_compat

Remove <memory> usages from abg_compat

std::shared_ptr, std::weak_ptr, std::dynamic_pointer_cast,
std::static_pointer_cast are now provided through the language standard,
hence remove the compatibility code for <memory> and adjust all users
accordingly.

	* include/abg-cxx-compat.h: Drop compatibility layer for <memory>.
	* include/abg-diff-utils.h: migrate abg_compat use to std.
	* include/abg-fwd.h: Likewise.
	* include/abg-ini.h: Likewise.
	* include/abg-interned-str.h: Likewise.
	* include/abg-libxml-utils.h: Likewise.
	* include/abg-libzip-utils.h: Likewise.
	* include/abg-regex.h: Likewise.
	* include/abg-reporter.h: Likewise.
	* include/abg-sptr-utils.h: Likewise.
	* include/abg-tools-utils.h: Likewise.
	* include/abg-workers.h: Likewise.
	* src/abg-comp-filter.cc: Likewise.
	* src/abg-comparison-priv.h: Likewise.
	* src/abg-dwarf-reader.cc: Likewise.
	* src/abg-ir.cc: Likewise.
	* src/abg-reader.cc: Likewise.
	* src/abg-suppression.cc: Likewise.
	* src/abg-tools-utils.cc: Likewise.
	* src/abg-writer.cc: Likewise.
	* tests/test-diff-filter.cc: Likewise.
	* tests/test-diff-pkg.cc: Likewise.
	* tests/test-diff-suppr.cc: Likewise.
	* tests/test-read-dwarf.cc: Likewise.
	* tests/test-read-write.cc: Likewise.
	* tests/test-types-stability.cc: Likewise.
	* tests/test-write-read-archive.cc: Likewise.
	* tools/abicompat.cc: Likewise.
	* tools/abidiff.cc: Likewise.
	* tools/abidw.cc: Likewise.
	* tools/abilint.cc: Likewise.
	* tools/abipkgdiff.cc: Likewise.

Signed-off-by: Matthias Maennich <maennich@google.com>