Prepare building ARM RPM
Prepare building ARM RPM

With these changes build works up to some point. patchelf
was actually not used, and with recent Julia commits it's
no longer downloaded automatically when USE_SYSTEM_PATCHELF=1.

yuyichao/julia-buildbot,kshyatt/julia-buildbot,staticfloat/julia-buildbot,staticfloat/julia-buildbot,yuyichao/julia-buildbot,kshyatt/julia-buildbot