EXTSynthesize: staticify the unique key
EXTSynthesize: staticify the unique key

Identifiers have extern linkage by default, which is bad news bears.
WPDreamMelody/libextobjc,liuruxian/libextobjc,sunfei/libextobjc,bboyesc/libextobjc,telly/libextobjc,KBvsMJ/libextobjc,sandyway/libextobjc,goodheart/libextobjc,sanojnambiar/libextobjc,jiakai-lian/libextobjc