Can not flash stm32vl-discovery via `make flash` in the fancyblink example

[bstaletic]

Currently, I see a few problems with make flash for STM32F4VL:

1. flossjtag has been moved in openocd to ftdi/flossjtag, so it can not be found currently. This affects 6 Makefiles
2. Even when changed to ftdi/flossjtag, the STM32F1VL-Discovery can not be flashed. Switching to stlink interface worked.

I can make appropriate pull requests, but I can not test whether other boards work with ftdi/flossjtag.

For posterity, here's the link to flossjtag.cfg and stm32/f1/Makefile.include:
https://github.com/openocd-org/openocd/blob/master/tcl/interface/ftdi/flossjtag.cfg
https://github.com/libopencm3/libopencm3-examples/blob/master/examples/stm32/f1/Makefile.include#L31

And here is the list of all references to flossjtag:

tiva/lm3s/Makefile.include:31:19:OOCD_INTERFACE ?= flossjtag
lpc/lpc17xx/Makefile.include:32:19:OOCD_INTERFACE       ?= flossjtag
lpc/lpc13xx/Makefile.include:31:19:OOCD_INTERFACE       ?= flossjtag
lpc/lpc43xx/Makefile.include:34:19:OOCD_INTERFACE       ?= flossjtag
stm32/f2/Makefile.include:33:19:OOCD_INTERFACE  ?= flossjtag
stm32/f1/Makefile.include:31:19:OOCD_INTERFACE  ?= flossjtag

[karlp]

The examples repo is effectively unmaintained due to the amount of copy-pasta across all the examples. If you want to test a blink andyour toolchain, I recommend https://github.com/libopencm3/libopencm3-miniblink/ instead.