Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

Update lualoader test script a little bit

Use userboot.so from the test directory if possible, fall back to .OBJDIR.
This avoids a problem that we've had since userboot coexistence was added,
where userboot.so alone no longer exists in the .OBJDIR but is instead just
a link installed later.

lua-test: Image the loader test directory if it doesn't exist yet

Default to /tmp/loadertest for lua test scripts

A quick test script that we can run to use userboot's test mode to
excersize the load loader. Assumes that we already have a suitable
root area that you pass in with the first arg.