[Windows] Add support of watchpoints to ProcessWindows
This patch adds support of watchpoints to the old ProcessWindows plugin.
The ProcessWindows plugin uses the RegisterContext to set and reset
watchpoints. The RegisterContext has some interface to access watchpoints,
but it is very limited (e.g. it is impossible to retrieve the last triggered
watchpoint with it), that's why I have implemented a slightly different
interface in the RegisterContextWindows. Moreover, I have made the
ProcessWindows plugin responsible for search of a vacant watchpoint slot,
because watchpoints exist per-process (not per-thread), then we can place
the same watchpoint in the same slot in different threads. With this scheme
threads don't need to have their own watchpoint lists, and it simplifies
identifying of the last triggered watchpoint.
Reviewers: asmith, stella.stamenova, amccarth
Reviewed By: amccarth
Subscribers: labath, zturner, leonid.mashinskiy, abidh, JDevlieghere, lldb-commits
Differential Revision: https://reviews.llvm.org/D67168