cascade support in backend (xchesscc_wrapper)

[jackl-xilinx]

Add cascade support for the operations AIE.putCascade and AIE.getCascade. It creates symbols llvm__aie__put__mcd and llvm__aie__get__scd which is not recognized. Error message when running aiecc.py is:

Error: undefined symbol "llvm___aie___get___scd"
... Symbol is referenced in file   : acdc_project/input.o (input.o)
... Symbol is referenced in : core_2_3 @ offset 80
Error: in "core_2_3.elf.map": Linking ended with errors, check the map file for an overview of already mapped symbols
xchesscc Failed 
The Program xchesscc has encountered an unexpected error exiting ... xchesscc Failed 
Error: undefined symbol "llvm___aie___put___mcd"
... Symbol is referenced in file   : acdc_project/input.o (input.o)
... Symbol is referenced in : core_1_3 @ offset 112
Error: in "core_1_3.elf.map": Linking ended with errors, check the map file for an overview of already mapped symbols
xchesscc Failed 
The Program xchesscc has encountered an unexpected error exiting ... xchesscc Failed 

bug.tar.gz