tree f2b390ca12e79d546917bfd536a7e7520d9d7ecc
parent 4072bec51e34019d1fd45fb839e9247f2a2b538b
author Darryl Green <darryl.green@arm.com> 1557403385 +0100
committer Darryl Green <darryl.green@arm.com> 1557404756 +0100

Only use submodule if present

Enabling the USE_CRYPTO_SUBMODULE option causes problems if the
crypto submodule isn't present. For example, when building
mbed-crypto as a submodule, it should use error.c from the parent
project if USE_CRYPTO_SUBMODULE is set. However if the parent
project isn't present, then the build will fail. Only enable it
if the submodule actually exists.