Try to support OldFunctions

rtree-c/src/ReduceC.hs

rtree-c/test/cases/small/oldfun.c

rtree-c/test/expected/oldfun/main.c

rtree-c/test/expected/oldfun/reduction/r0000.c

rtree-c/test/expected/oldfun/reduction/r0001.c

rtree-c/test/expected/oldfun/reduction/r0010.c

rtree-c/test/expected/oldfun/reduction/r0011.c

rtree-c/test/expected/oldfun/reduction/r010.c

rtree-c/test/expected/oldfun/reduction/r011.c

rtree-c/test/expected/oldfun/reduction/r10.c

rtree-c/test/expected/oldfun/reduction/r11.c

rtree-c/test/src/ReduceCSpec.hs