Decompress segfaults on Solaris Sparc

[jeroen]

Possibly related to #203

> brotli_decompress(y)

 *** caught bus error ***
address ffbfc093, cause 'invalid alignment'

Traceback:
 1: .Call(R_brotli_decompress, buf)
 2: brotli_decompress(y)

[eustas]

Try to compile with -DBROTLI_BUILD_PORTABLE option.

[jeroen]

This indeed seems to help. Does this flag have any side effects? Why is it not the default?

[eustas]

We haven't taken Sparc CPUs into account.
I'll prepare patch that disables unaligned reads on Sparc CPUs.

[eustas]

Now SPARC and ARMv6 build in "portable" mode by default.

We're going to replace black-listing with white-listing, so unrecognized architectures would be built in "portable" mode.

Thank you for pointing the problem out.