Self test failing on arm

[jeremysanders]

The embedding self test is failing on ARM due to rounding issues. The standard self tests use a hack to make the floats have the same ascii representation, which isn't applied in the embedding self test.

Possible fixes:

• Somehow insert the hack into the running remote Veusz
• Only do the self test on x86/x86_64
• Make the self test output comparison more lenient