Many changes made

rtree-c/src/ReduceC.hs

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

rtree-c/test/expected/add/reduction/r0000000000.c

rtree-c/test/expected/add/reduction/r0000000001.c

rtree-c/test/expected/add/reduction/r0000000010.c

rtree-c/test/expected/add/reduction/r0000000011.c

rtree-c/test/expected/add/reduction/r0000000100.c

rtree-c/test/expected/add/reduction/r0000000101.c

rtree-c/test/expected/add/reduction/r0000000110.c

rtree-c/test/expected/add/reduction/r0000000111.c

rtree-c/test/expected/add/reduction/r0000001000.c

rtree-c/test/expected/add/reduction/r0000001001.c

rtree-c/test/expected/add/reduction/r0000001010.c

rtree-c/test/expected/add/reduction/r0000001011.c

rtree-c/test/expected/add/reduction/r0000001100.c

rtree-c/test/expected/add/reduction/r0000001101.c

rtree-c/test/expected/add/reduction/r000000111.c

rtree-c/test/expected/add/reduction/r000001.c

rtree-c/test/expected/add/reduction/r0000100000.c

rtree-c/test/expected/add/reduction/r0000100001.c