While some of the examples include a "board.ld" style file, some of them were pointing to the libopencm3 provided chip specific ld scripts. When TOOLCHAIN_DIR has been overridden, those paths were no longer valid/correct.
------------------------------------------------------------------------------ README ------------------------------------------------------------------------------ This is the smallest-possible example program using libopencm3. It's intended for the ST STM32L-DISCOVERY eval board. It should blink the blue LED on the board.