Make file on Ubuntu 20.04

[indrajitbarve]

I tried to compile the codes. I got some undefined reference error and in the Makefile, I changed the following and I could able to run it.
FROM

gcc -lOpenCL -lm -L /lib/x86_64/ main_wrapper.o amd_firepro_error_code_list_for_opencl.o input_generator.o gpu_data_reorg.o gpu_cpu_helpers.o cpu_corr_test.o -o correlator_test

TO

gcc main_wrapper.o amd_firepro_error_code_list_for_opencl.o input_generator.o gpu_data_reorg.o gpu_cpu_helpers.o cpu_corr_test.o -o correlator_test -lOpenCL -lm -L /lib/x86_64/