opencm: libopencm3 submodule build fails when running "make libopencm3"

[vatrat]

make libopencm3 gives an error.

> make libopencm3
if [ ! -f libopencm3/Makefile ]; then \
        git submodule init; \
        git submodule update; \
fi
Submodule path 'libopencm3': checked out '580a2a4a63cad6ca32ac837cf6d1c64664ce80f3'
make -C libopencm3 lib/stm32/f1
  GENHDR  include/libopencm3/lm3s/irq.json
  GENHDR  include/libopencm3/lpc13xx/irq.json
  GENHDR  include/libopencm3/lpc17xx/irq.json
  GENHDR  include/libopencm3/vf6xx/irq.json
  GENHDR  include/libopencm3/efm32/gg/irq.json
  GENHDR  include/libopencm3/efm32/g/irq.json
  GENHDR  include/libopencm3/efm32/lg/irq.json
  GENHDR  include/libopencm3/efm32/tg/irq.json
  GENHDR  include/libopencm3/lpc43xx/m0/irq.json
  GENHDR  include/libopencm3/lpc43xx/m4/irq.json
  GENHDR  include/libopencm3/sam/3a/irq.json
  GENHDR  include/libopencm3/sam/3n/irq.json
  GENHDR  include/libopencm3/sam/3s/irq.json
  GENHDR  include/libopencm3/sam/3u/irq.json
  GENHDR  include/libopencm3/sam/3x/irq.json
  GENHDR  include/libopencm3/sam/d/irq.json
  GENHDR  include/libopencm3/stm32/f0/irq.json
  GENHDR  include/libopencm3/stm32/f1/irq.json
  GENHDR  include/libopencm3/stm32/f2/irq.json
  GENHDR  include/libopencm3/stm32/f3/irq.json
  GENHDR  include/libopencm3/stm32/f4/irq.json
  GENHDR  include/libopencm3/stm32/f7/irq.json
  GENHDR  include/libopencm3/stm32/l0/irq.json
  GENHDR  include/libopencm3/stm32/l1/irq.json
  GENHDR  include/libopencm3/stm32/l4/irq.json
  BUILD   lib/stm32/f1
/bin/sh: -c: line 1: unexpected EOF while looking for matching `"'
make[1]: *** [Makefile:68: lib/stm32/f1] Error 2
make: *** [Makefile:18: libopencm3] Error 2

Running git submodule update --init works properly, but running make libopencm3 afterward gives the same error, only without the line Submodule path 'libopencm3': checked out '580a2a4a63cad6ca32ac837cf6d1c64664ce80f3'.