GCC（GNU Compiler Collection）在GCC 7移除了对Java的前端gcj支持, GCC 6之前还可以用gcj.
详情参考：As of GCC 7, the GCC Java frontend and associated libjava runtime library have been removed from GCC
GCC（GNU Compiler Collection）在GCC 7移除了对Java的前端gcj支持, GCC 6之前还可以用gcj.
详情参考：As of GCC 7, the GCC Java frontend and associated libjava runtime library have been removed from GCC
