scripts/tags.sh: include compat_sys_* symbols in the generated tags

Since the kernel now has a COMPAT_SYSCALL infrastructure via commit
46836613

 ("COMPAT_SYSCALL_DEFINE: infrastructure"), add the
corresponding regex for generating compat_sys_* symbols in the tags
files (similar to sys_*).

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>