Just because the far left has discovered a hatred for law enforcement doesn't mean that's a GOP voting bloc. Cops are government employees who don't make a whole lot, and I'd bet they vote Dem, especially in big cities. They CERTAINLY vote to the left of business types.
Umm did you see the reaction to De Blasio from the NYPD? White cops at least tend to be very racist in general and have a conservative attitude towards society in general believing themselves to be serving the "upstanding citizens of the community." I think are most likely overwhelmingly Republican.