Target function selection based on calling function in call stack

[haxmeadroom]

Allow for targeting functions based on the calling function. For example, if our dirty function is fread() and the function we care about is AddFontResourceEx() , add the ability to only target when fread() is called from AddFontResourceEx(). Not sure if dynamorio support this, may have to unwind the stack and find calling functions. This is related to #42 .

[ehennenfent]

DynamoRIO has a couple of open issues for walking back call stacks. It might not be impossible to get decent results, but would likely require a lot of effort.

DynamoRIO/drmemory#823
DynamoRIO/dynamorio#2414

[woodruffw]

Closing since we've implemented an adequate function targeting strategy (please re-open if this needs revisiting).