This also adds MachErrorMessage(), a test-only function that’s a
dependency of TaskMemory’s test, and related test-only error message
functions.
TEST=util_test TaskMemory.*
R=rsesek@chromium.org
Review URL: https://codereview.chromium.org/438993002
The final range check needs to check that the value fits in a size_t,
because that’s what StringFileWriter uses for its offset_.
TEST=util_test StringFileWriter.SeekInvalid
R=rsesek@chromium.org
Review URL: https://codereview.chromium.org/434103003