linknamespace: whitelist re_syntax_options.

linknamespace: whitelist re_syntax_options.

This patch adds re_syntax_options (bug 18442) to the set of symbols
that are whitelisted in the linknamespace tests because, while the
references to them are genuine bugs that should be fixed, the
involvement of data symbols makes them harder to fix than most such
bugs.

Tested for x86_64 and x86.

	* conform/linknamespace.pl (@whitelist): Add re_syntax_options.
	* conform/Makefile (test-xfail-UNIX98/regex.h/linknamespace):
	Remove variable.
	(test-xfail-XOPEN2K/regex.h/linknamespace): Likewise.
	(test-xfail-POSIX2008/regex.h/linknamespace): Likewise.
	(test-xfail-XOPEN2K8/regex.h/linknamespace): Likewise.