uLUt allows minimal build suitable for mcs51 SDCC target.

The mcs51 build requires SDCC with matured inline support
and C99 support. The proposed inline fixes can be found
in discussion under bug #1767885

  Parameters lost from scope of intermediate inline function

Next options has been included in config.omk to build this
minimal uLUt version.

CONFIG_OC_ULUT=y
CONFIG_OC_ULUTMINIMAL=y

CFLAGS  += --std-c99

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>