[SV 56449] (Windows) Use slow path if '%' appears in the command

[SV 56449] (Windows) Use slow path if '%' appears in the command

* src/job.c (sh_chars_dos): Add '%' as a special character
* src/job.c (construct_command_argv_internal): Check for '%' in quotes

For the windows version of make, a recipe line cannot be executed
diretly by make (without a shell) if a '%' character is present. This
character starts a cmd.exe escape sequence.

Signed-off-by: Christian Eggers <ceggers@arri.de>
Copyright-paperwork-exempt: yes