* hw/kdrive/src/Makefile.am: use fb/fbcmap_mi.c
and not fb/fbcmap.c. This allows kdrive to take advantage of
extensions redefining the entry points of micmap.c stuff.
For instance it allows Xephyr to have a working GL, which is not
possible otherwise, because GL redefines mInitVisualsProc
to initialise its visuals.