for -pause_at_*, present app context inside debugger, not tool context

_From [rnk@google.com](https://code.google.com/u/rnk@google.com/) on September 22, 2011 16:10:18_

This feature should roughly mirror --gdb-attach=yes for memcheck. We already have -pause_at_uninitialized/unaddressable, but attaching in this way puts the user a few frames inside of DrMemory tool code. --gdb-attach sets up gdb so that it sees the original application context, ie all of the application registers, xsp, xip, etc, and the user can begin a normal debugging session as if the tool wasn't there.

I have found this really useful for being able to actually print out values when I have say an out of bounds access, for example. If you don't have this, you only get the information the tool gives you, while the debugger allows you to ask more questions.

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=600_