Map armv6l host architecture to arm target architecture.

Build should now success on Rasperry Pi.
Don't compile breakpad if we are running on ARM and use a noop crash report
backend.

This is a simple workaround because this project includes an old version of
breakpad which doesn't include support for ARM.

New versions of breakpad should support ARM
(https://code.google.com/p/google-breakpad/source/browse/trunk/src/tools/linux/md2core/minidump-2-core.cc#334),
so another (better) approach would be to upgrade breakpad.
Merge pull request #42 from Kami/fix_rasperry_pi_arm_build

Make build work on Rasperry Pi (ARM)