Sometimes, when building the shared target with crypto submodule, one could
get an "No rule to make target '../crypto/library/libmbedcrypto.so'" error.
This is due to two reasons - building in parallel and (probably) an
incomplete/incorrect list of dependencies for certain targets. The proposed
solution is to disable parallel builds with crypto submodule for now.
An issue has been raised here: https://github.com/ARMmbed/mbedtls/issues/2634
87615770c7