[node_build] cross compiling support for OpenWRT and NaCL (only)

[node_build] cross compiling support for OpenWRT and NaCL, cjdroute, mostly everything else please see https://ezcrypt.it/KZ7n#JtLzL131JvqkdGgL8EHGk1FE for NaCL speed increase benchmark on mips32r2 (Atheros AR7240 Buffalo WHR-HP-GN)

typo

[node_build] *DUPE* clashed with @interfect close of #458

Also returned all compiler flags to Builder