linux/mips: Unbreak the build
linux/mips: Unbreak the build

Specifically, uname syscall support on Linux is controlled by a build
tag white list, and both mips64 platforms were missing from the list.

Jean-Daniel/node_exporter,joehandzik/node_exporter,chosenken/node_exporter,ema/node_exporter,bs-github/node_exporter,mslocrian/flexswitch_exporter,Jean-Daniel/node_exporter,siavashs/node_exporter,siavashs/node_exporter,derekmarcotte/node_exporter,prometheus/node_exporter,siavashs/node_exporter,derekmarcotte/node_exporter,ema/node_exporter,ema/node_exporter,joehandzik/node_exporter,bs-github/node_exporter,prometheus/node_exporter,derekmarcotte/node_exporter,joehandzik/node_exporter,prometheus/node_exporter,chosenken/node_exporter,Jean-Daniel/node_exporter,mslocrian/flexswitch_exporter,chosenken/node_exporter,ema/node_exporter,derekmarcotte/node_exporter,bs-github/node_exporter,joehandzik/node_exporter,Jean-Daniel/node_exporter,knweiss/node_exporter,chosenken/node_exporter,knweiss/node_exporter,siavashs/node_exporter,bs-github/node_exporter,knweiss/node_exporter,knweiss/node_exporter