build.linux32ARMv[67]/pharo.cog.spur/build*/mvm is lacking -DIMMUTABILITY. c.f. -DIMMUTABILITY=1 in build.win*/pharo.cog.spur/Makefile build.macos*pharo.cog.spur/Makefile.
I wish someone would volunteer to rewrite the linux build system to copy the much nicer scheme used in Mac OS and Windows.