Fix bug: when checking compatibility between GLOBAL and EXTERNAL variables, must only enforce GLOBAL CONSTANT => EXTERNAL CONSTANT.
Reverse CONSTANT implication is not enforced, and neither is RETAIN compatibility.
syntax: glob
.project
*~
*.a
.dep
*.Po
autom4te.cache
Makefile
config.log
stamp-h1
config.status
syntax: regexp
\.o$
^iec2c$
^iec2iec$
\.depend$
^stage1_2/iec_bison.cc
^stage1_2/iec_bison.h
^stage1_2/iec_flex.cc
^config/config.h