Corrected dependencies of make distrib, and removed it from the clean list.
Made test scripts more robust, and also generate a distribution
Merge branch 'master' of github.com:halide/Halide
Made blur app robust to absence of openmp
Improved asm sniffing in simd_op_check so it doesn't miss vst2
Reorganized CodeGen_ARM so that it doesn't take forever to compile with clang