Historically $(OBJECTDIR) was created when Makefile.include is read. A
consequence is that combining "clean" with "all" (or any other build
target) results in an error because the clean removes the object
directory that is required to exist when building dependencies.
Creating $(OBJECTDIR) on-demand ensures it is present when needed.
Removed creation of $(OBJECTDIR) on initial read, and added an order-only
dependency forcing its creation all Makefile* rules where the target is
explicitly or implicitly in $(OBJECTDIR).
- For the CC2538, simplify handling of USB_CDC_ACM_LINE_STATE
events. Ignore the Carrier Control (RTS) bit when receiving
a SET_CONTROL_LINE _STATE request, we are a full duplex device.
- Improve behaviour of the CC2531 USB stick when there is no
process on the host to read IN data. Basically, we adopt the
CC2538 approach and we only send data when a DTE is present
