PATCH(jwoglom): ExtractFrames is split-out code from ExtractStacktrace which allows for frame extraction to be performed given glog PC pointers.

ExtractStacktrace creates a new Stacktrace based on the given error.

GetXErrorStackTrace returns a combined stack trace incorporating the stack of the logging call site and that of the error it's logging.

GopathRelativeFile sanitizes the path to remove GOPATH and obtain the import path.

GuessAbsPath guesses the proper absolute path if it is not provided, making a best-effort guess so that Sentry can attempt to augment the error with source code.

NewFrame assembles a stacktrace frame out of runtime.Frame.

SourceFromStack retrieves the function and line where the event was logged from in the format "file.Function:118".