Fix watchpoint check to use watchpoint ranges

Summary: Watchpoints, unlike breakpoints, have an address range. This patch changes WatchpointList::FindByAddress() to match on any address in the watchpoint range, instead of only matching on the watchpoint's base address.

Reviewers: clayborg

Subscribers: lldb-commits

Differential Revision: http://reviews.llvm.org/D14932

llvm-svn: 254931