Add an helper function to build external dependencies
Summary
Until now the external dependencies are manually added where needed, for example in the RPC modules built for the back-end board. That can lead to builds with a deep filesystem structure which is harder to debug (as in !44 (merged) with the rpcsvc
executable).
What is the expected correct behavior?
A cmake
helper could be implemented in order to (1) ensure that the external modules are added only once to a given project and (2) that they are built is a well know-location (.e.g ${CMAKE_PROJECT_BINARY_DIR}/_extern/${EXTERNAL_MODULE_NAME}
).