Add configuration options for Haskell compilation variants
Add configuration options for Haskell compilation variants

Previously this was addressed by Makefile variables, which meant that
it was possible to build the same binary with different compilation
options without recompiling.

Signed-off-by: Petr Pudlak <9d19625f8ee825a2c398462ed335cbcf98f79c32@google.com>
Reviewed-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>

onponomarev/ganeti,leshchevds/ganeti,yiannist/ganeti,dimara/ganeti,ganeti-github-testing/ganeti-test-1,apyrgio/ganeti,mbakke/ganeti,yiannist/ganeti,yiannist/ganeti,apyrgio/ganeti,dimara/ganeti,andir/ganeti,grnet/snf-ganeti,leshchevds/ganeti,ganeti/ganeti,onponomarev/ganeti,mbakke/ganeti,mbakke/ganeti,grnet/snf-ganeti,ganeti-github-testing/ganeti-test-1,leshchevds/ganeti,ganeti/ganeti,bitemyapp/ganeti,ganeti/ganeti,andir/ganeti,andir/ganeti,bitemyapp/ganeti