Requested in #6 (Atheros AR9344). Chromium/cronet has no big-endian MIPS
toolchain, so the musl+naive path is impossible for this target; add it to
the plain cross-compile matrix instead as a pure-Go CGO_ENABLED=0 build —
statically linked (runs on musl/OpenWrt as-is), with with_naive_outbound
and with_purego dropped (purego has no mips port either). Everything else
matches the desktop tag set.
Verified locally: GOOS=linux GOARCH=mips GOMIPS=softfloat build with the
reduced tag set compiles clean; `file` reports ELF 32-bit MSB MIPS32,
statically linked.