patch 9.2.0434: cscope: filename interpreted by /bin/sh

patch 9.2.0434: cscope: filename interpreted by /bin/sh

Problem:  cs_create_connection() builds the cscope command by
          interpolating csinfo[i].fname (and ppath, flags) into a
          string and lets the shell parse it.  Shell metacharacters
          in a database filename are therefore evaluated by /bin/sh
          before cscope is exec'd, rather than being passed through as a
          literal path (q1uf3ng)
Solution: Build argv directly and execvp() the cscope binary
          without an intervening shell.

closes: #20119

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>