OpenContrail Compile and Build with debug enabled

https://github.com/Juniper/contrail-controller/blob/8cc4abe1d8422ce515673a79bc614b27c4fb088e/lib/hiredis/SConscript#L14
env.Append(CCFLAGS = ['-g'])

https://github.com/Juniper/contrail-controller/blob/c12548ab0adaf3706987a954529e5315f0c5336d/src/query_engine/SConscript#L153
env.AppendUnique(CCFLAGS='-g')

http://www.scons.org/doc/0.96/HTML/scons-user/c972.html

http://pages.cs.wisc.edu/~driscoll/software/scons/variables.html