Fix crash on enum name override
Fix crash on enum name override

When a explicitly assigned value was renamed and followed by implicit
values, the starting value was not looked up correctly.

Signed-off-by: Joshua Kahn <b68d3c7251d7cf29442c0ad8937e1a6fcc8b4882@barracuda.com>

barracudanetworks/constantsgen,barracudanetworks/constantsgen,barracudanetworks/constantsgen