Set EXAMPLE_PROGRAMS in one line.

Signed-off-by: Zhiyi Sun <zhiyisun@gmail.com>

examples/networking/CMakeLists.txt

 set(EXAMPLE_FILES simulation.py)
-set(EXAMPLE_PROGRAMS simple_tc.py)
-set(EXAMPLE_PROGRAMS ${EXAMPLE_PROGRAMS} tc_perf_event.py)
+set(EXAMPLE_PROGRAMS simple_tc.py tc_perf_event.py)
 install(FILES ${EXAMPLE_FILES} DESTINATION share/bcc/examples/networking)
 install(PROGRAMS ${EXAMPLE_PROGRAMS} DESTINATION share/bcc/examples/networking)