Avoid unncessary use of double in the kernel. With this change,
a LLVM build kernel fully works on TWRP1025.
Fix c&p error: libisc.a->libirs.a
In case of no dup2'd fd's, make sure that F_CLOSEM for the
rump kernel starts from 0.

Fixes rumphijack fdoff test (notably, this bug had nothing to do with
fdoff, and was exposed >3 years after writing the test when rump kernels
started providing fd's 0/1/2)
Update hardcoded fd expectations now that rump kernels open 0/1/2.
(since we exec, it's convenient to just assume the values of first 4 fds)
Fix for PR/49107.
Make sure pmap_copy_page_xscale clears the ptes afters its done with them.
SS device detection needs more work. #if 0 previous attempt for now.

PR/49106: panic: ehci_open: bad device speed 4
add PRAM access commands