Expose hit count via SBBreakpointLocation.

Summary:
SBBreakpointLocation exposed the ignore count, but didn't expose
the hit count. Both values were exposed by SBBreakpoint and
SBWatchpoint, so this makes things a bit more consistent.

Reviewers: lldb-commits

Subscribers: lldb-commits

Differential Revision: https://reviews.llvm.org/D31283

llvm-svn: 308480