patch 9.2.0202: [security]: command injection via newline in glob()

patch 9.2.0202: [security]: command injection via newline in glob()

Problem:  The glob() function on Unix-like systems does not escape
          newline characters when expanding wildcards. A maliciously
          crafted string containing '\n' can be used as a command
          separator to execute arbitrary shell commands via
          mch_expand_wildcards(). This depends on the user's 'shell'
          setting.
Solution: Add the newline character ('\n') to the SHELL_SPECIAL
          definition to ensure it is properly escaped before being
          passed to the shell (pyllyukko).

closes: #19746

Github Advisory:
https://github.com/vim/vim/security/advisories/GHSA-w5jw-f54h-x46c

Signed-off-by: pyllyukko <pyllyukko@maimed.org>
Signed-off-by: Christian Brabandt <cb@256bit.org>