StacktraceAddressSignature is missing on many ARM reports

None of the armhf test crashes built in https://code.launchpad.net/~daisy-pluckers/+archive/daisy-seeds have a StacktraceAddressSignature. For precise and quantal an important fix was fixed in Raring and currently being SRUed to precise and quantal in bug 1084996, but that doesn't seem to be enough for armhf.

This is because Apport currently makes the assumption that the last field (the file path) is separated from the other fields by at least four spaces, which is the case on x86 (where there are some 15 spaces). However, on armhf there are only three, so the parser did not recognize these lines.

FIX: http://bazaar.launchpad.net/~apport-hackers/apport/trunk/revision/2563 (which just reduces the number of expected spaces from 4 to 2, and adds a test case from a real-life ARM crash)

SRU TEST CASE:
Above patch includes a test case, but a manual one is:
- Generate a crash on an armhf machine, with e. g.: dash -c 'kill -SEGV $$'
- Let Apport pop up and display the details
- With the current Apport version, it most probably does not have a StacktraceAddressSignature field; with the -proposed package it should have one.