[utils] Fix incompatibility of bisect[-skip-count] with Python 3

Summary:
This change replaces the print statements with print function calls
and also replaces the '/' operator (which is integer division in Py2,
but becomes floating point division in Py3) with the '//' operator
which has the same semantics in Py2 and Py3.

Reviewers: greened, michaelplatings, gottesmm

Reviewed By: greened

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68138

llvm-svn: 373759