Soc2c: Fix 2 bugs in the C code generation.

The first one in Soc2cIdent.type_to_short_string when enum and int were both
translated by "i" ; as a consequence, some different soc ctx get the same name.

The second one was due to the fact that car ident in gao switches were
printed incorrectly (missing "ctx->" or "node_no_mem_ctx.").

nb:  unexpected failures 162-> 149