Prevent loading arbitrary executable code based on config at runtime,
while allowing libraries to be specified at compile time when they are
known in advance.
Add the ability to configure libraries to load at compile time.
* CONFIG_PKCS11_ENGINE_PATH - pkcs11_engine library location.
* CONFIG_PKCS11_MODULE_PATH - pkcs11_module library location.
* CONFIG_OPENSC_ENGINE_PATH - opensc_engine library location.
Add flags with the ability to set each of the libraries to NULL and
prevent loading them at runtime.
* CONFIG_NO_PKCS11_ENGINE_PATH - prevents loading pkcs11_engine
library.
* CONFIG_NO_PKCS11_MODULE_PATH - prevents loading pkcs11_module
library.
* CONFIG_NO_OPENSC_ENGINE_PATH - prevents loading opensc_engine
library.
* CONFIG_NO_LOAD_DYNAMIC_EAP - prevents loading EAP libraries at
runtime.
Signed-off-by: David Ruth <druth@chromium.org>