Forward HUNTER_BASE value to all subprojects
Forward HUNTER_BASE value to all subprojects

Since HUNTER_BASE can have custom location (e.g. testing)
it need to be added to external toolchain.

isaachier/hunter,zhuhaow/hunter,lucmichalski/hunter,fwinnen/hunter,Knitschi/hunter,NeroBurner/hunter,ikliashchou/hunter,alamaison/hunter,fire-hunter/hunter,x10mind/hunter,mchiasson/hunter,xsacha/hunter,ledocc/hunter,ErniBrown/hunter,designerror/hunter,ikliashchou/hunter,ThomasFeher/hunter,shekharhimanshu/hunter,dvirtz/hunter,dmpriso/hunter,isaachier/hunter,designerror/hunter,dan-42/hunter,NeroBurner/hunter,Knitschi/hunter,NeroBurner/hunter,ingenue/hunter,ErniBrown/hunter,madmongo1/hunter,pretyman/hunter,akalsi87/hunter,daminetreg/hunter,vdsrd/hunter,akalsi87/hunter,RomanYudintsev/hunter,shekharhimanshu/hunter,ledocc/hunter,stohrendorf/hunter,jkhoogland/hunter,caseymcc/hunter,pretyman/hunter,x10mind/hunter,designerror/hunter,ruslo/hunter,mchiasson/hunter,xsacha/hunter,fwinnen/hunter,fwinnen/hunter,ikliashchou/hunter,stohrendorf/hunter,headupinclouds/hunter,ledocc/hunter,ruslo/hunter,isaachier/hunter,vdsrd/hunter,RomanYudintsev/hunter,fire-hunter/hunter,lucmichalski/hunter,vdsrd/hunter,shekharhimanshu/hunter,ikliashchou/hunter,RomanYudintsev/hunter,lucmichalski/hunter,ruslo/hunter,stohrendorf/hunter,ulricheck/hunter,dmpriso/hunter,dvirtz/hunter,ThomasFeher/hunter,madmongo1/hunter,dan-42/hunter,mchiasson/hunter,headupinclouds/hunter,alamaison/hunter,jkhoogland/hunter,ingenue/hunter,headupinclouds/hunter,sumedhghaisas/hunter,ingenue/hunter,sumedhghaisas/hunter,dan-42/hunter,sumedhghaisas/hunter,tatraian/hunter,xsacha/hunter,ErniBrown/hunter,madmongo1/hunter,dvirtz/hunter,NeroBurner/hunter,ulricheck/hunter,Knitschi/hunter,zhuhaow/hunter,isaachier/hunter,tatraian/hunter,dmpriso/hunter,fire-hunter/hunter,ingenue/hunter,daminetreg/hunter,pretyman/hunter,jkhoogland/hunter,akalsi87/hunter,madmongo1/hunter,caseymcc/hunter,xsacha/hunter,tatraian/hunter,dan-42/hunter,ErniBrown/hunter,daminetreg/hunter,alamaison/hunter,pretyman/hunter,ruslo/hunter,mchiasson/hunter,ThomasFeher/hunter,caseymcc/hunter,ulricheck/hunter,zhuhaow/hunter,x10mind/hunter