Fix dir name in tarball for SRPM
Fix dir name in tarball for SRPM

make light-source-dist uses the name of the current directory, which is "build",
while the .spec file says it should be "julia".

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