Fix ?/% mix-up in Perl_vms_start_glob.

Fix ?/% mix-up in Perl_vms_start_glob.

When it sees the unixy ? as a single-character wildcard rather than
the native %, it intended to leave it alone when the CRTL's extended
character set processing was enabled, but it was actually checking
for a different and unrelated feature setting (case preservation),
meaning it would substitute % for ? in some cases where it meant
not to.  This likely did no harm in most cases as LIB$FIND_FILE
will honor either, but if the pattern were to be re-used in a context
that required POSIX semantics, the ? really ought to be preserved
and now it is.

Broken in dca5a9130eb9e045fd52f88cf3dedee7093e19f7.