different between -L/libpath and /etc/ld.so.conf configure
/etc/ld.so.confisusedbythedynamiclinker(seemanpageld.so(8))tofigureoutwhichpathstosearchforyourlibraryfile.Thishappensatruntime. Youstillneedtopass-L/usr/local/libtogcc,whichwillpassitontold(seemanp