The -C crate_hash option does not work if multiple versions of the same
crate are being linked into a binary. This can happen if different
dependencies depend on different versions of the same crate. The -C
crate_hash argument causes all versions of a given crate to have the
same crate hash which in turn causes the compiler to select the wrong
one internally and crash. This works around issue #126 for Cargo builds
but does not fix the underlying cause.
