proc: adds pointer pinning to call injection

[aarzilli]

This commit adds a new mode to call injection. If the runtime.debugPinner
function is available in the target executable it obtains a pinner by
calling it and then uses it to pin the pointers in the results of call
injection.

This allows the code for call injection to be refactored to execute the
calls in the normal order, since it doesn't need to be concerned with having
space on the target's memory to store intermediate values.

Updates #3310

[aarzilli]

There's a rare failure that seems to be happening with this changeset and windows, I want to investigate it before merging.

[aarzilli]

There's a rare failure that seems to be happening with this changeset and windows, I want to investigate it before merging.

For the record: this issue was fixed. It was a preexisting issue exposed by this change where if we have to call injections happening simultaneously it's possible that when we resume execution of the target one of them will not make any progress (the other stops the process before the thread executing the first one is ever scheduled).

When that happened we didn't notice and assumed that both had progressed. The solution is to check for thread.SoftExc() so that we only take into consideration threads for which we received a breakpoint exception.

[derekparker]

LGTM