fixes #134 cstyle: check binary op continuations

Fixes #134.

I tested this by running against `usr/src/uts/i86pc/` and verifying
that reports of `binary operator at start of continuation` were not
false alarms. E.g., if a continuation starts with a dereference like
`*pointer` then it should not be flagged. It turns out there are
plenty of areas in UTS that violate this particular cstyle rule.

    find usr/src/uts/i86pc/ -name "*.c" | xargs -L1 perl usr/src/tools/scripts/cstyle.pl -cpv | grep 'binary op' -C2
Could you use character classes to improve readability?  Also, "|" is always wrong at the start of a line, as is >, <, and /, so we can simplify the regex.  Alternative approach:

if (/^\s*(&[ &]|[<>\|/^]|[\*\+-&] |[=!]=)  ...

Hmm... expanded form might be more readable, but my approach is possibly more efficient.  Regexes are wonderful.  Regexes suck.  Go figure. :-)