cc: Fix compile warning (#2346)
cc: Fix compile warning (#2346)

Add corresponding ifdef macro to get ride of the follow warning.

/home/lecopzer/workspace/mybcc/src/cc/bcc_debug.cc: In member function ‘void ebpf::SourceDebugger::dump()’:
/home/lecopzer/workspace/mybcc/src/cc/bcc_debug.cc:186:16: warning: unused variable ‘SectionID’ [-Wunused-variable]
       unsigned SectionID = get<2>(section.second);
                ^~~~~~~~~
brendangregg/bcc,brendangregg/bcc,iovisor/bcc,tuxology/bcc,tuxology/bcc,iovisor/bcc,iovisor/bcc,brendangregg/bcc,tuxology/bcc,brendangregg/bcc,brendangregg/bcc,tuxology/bcc,iovisor/bcc,tuxology/bcc,iovisor/bcc