Bug 837448 - fix comparing garbage data in sms_address_eq. r=hsinyi

The |addr1->len| is the number of digits, and SMS-ADDRESS packs two
digits into one octet.  So sometimes the garbage data at the end fail
the comparison, which in turn fails |sms_receiver_find_p()|, and then
results in a new fragment created with wrong parameter.
Merge pull request #40 from vicamo/bugzilla/837448/fix-intermittent-test_emulator_loopback-failure

Bug 837448 - fix comparing garbage data in sms_address_eq. r=hsinyi