Do -Wmissing-prototypes only with RUMPRUN_PRESENT=yes
Do -Wmissing-prototypes only with RUMPRUN_PRESENT=yes

Seems like out copy of compiler-rt has some missing-protos issues,
and prolly not worth fixing them.

ujamjar/rumpuser-baremetal,ujamjar/rumpuser-baremetal,rumpkernel-attic/rumprun-baremetal,rumpkernel-attic/rumprun-baremetal,rumpkernel-attic/rumprun-baremetal,ujamjar/rumpuser-baremetal