patch 9.1.0426: too many strlen() calls in search.c

patch 9.1.0426: too many strlen() calls in search.c

Problem:  too many strlen() calls in search.c
Solution: refactor code and remove more strlen() calls,
          use explicit variable to remember strlen
          (John Marriott)

closes: #14796

Signed-off-by: John Marriott <basilisk@internode.on.net>
Signed-off-by: Christian Brabandt <cb@256bit.org>