1. When startoffset was not zero and the pattern began with ".*", PCRE
was not trying to match at the startoffset position, but instead was
moving forward to the next newline as if a previous match had failed.
2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g
and /G, and could get into a loop if a null string was matched other
than at the start of the subject.
