Submodule updates are not triggered if submodule library exists

[chrisdigity]

The easy fix for this is to remove all build (and subsequent library) files from submodules, forcibly triggering the required submodule update on the next build command by simply running make cleanall.
However, the makefile is supposed to account for and update submodules accordingly.

[chrisdigity]

Having considered removing this issue, I again encounter it in a related process...

Form a fresh clone:

• build submodule libraries
• checkout different branch that uses different versions of the submodules
• try to rebuild
  ... even a recursive clean won't be enough, the submodules are stuck in their previous state.

Need some method of identifying when the current submodule hash does not align with the current base repo's desired submodule configuration.

Current workaround would be to delete the contents of the submodule folders and re-initialize, but maybe there's another way...

[chrisdigity]

$(SUBSOURCEDIRS): %:
	git config submodule.recurse true
	git submodule update --init --recursive

... by setting configuration to recurse submodules immediately BEFORE submodule initialization, any subsequent checkouts appear to respect the appropriate submodule revisions.

Still pondering whether this is appropriate though...