New plugin interface to get list of symbols wrapped with --wrap option.

2018-02-22  Sriraman Tallam  <tmsriram@google.com>

	* plugin.cc (get_wrap_symbols): New plugin interface.
	(load): Add get_wrap_symbols to transfer vector.
	* plugin-api.h (ld_plugin_get_wrap_symbols): New plugin interface.
	* testsuite/plugin_test.c (onload): Call and check get_wrap_symbols
	interface.
	* testsuite/plugin_test_wrap_symbols.sh: New test script.
	* testsuite/plugin_test_wrap_symbols_1.cc: New file.
	* testsuite/plugin_test_wrap_symbols_2.cc: New file.
	* testsuite/Makefile.am (plugin_test_wrap_symbols): New test.
	* testsuite/Makefile.in: Regenerate.

(cherry picked from commit 0b65c07b)