libLEX_CSNEW.so shipped with an unresolved symbol. decode_cmd_type is only
called when the generator reports an unreachable statement after a RETURN, so
the plug-in loaded normally and then died part way through a module with
libLEX_CSNEW.so: undefined symbol: decode_cmd_type
leaving a half written output file behind.
fgl_enums.c and fgl_enums.h are copied here from lex_esqlc rather than linked
from it: the lex plug-ins are built and shipped independently, so one must not
depend on another's objects. The enums come from the shared compiler headers,
so the two copies cannot drift apart silently - a new enumerator makes both
fail to build in the same way.
