am 226e1671: Merge remote-tracking branch \'toybox/master\' into HEAD

* commit '226e167128144090a95197f5d30b7e6d607d52ec':
  Fix mv on overwrite.
  Add portability.h glue to let uptime build without TOYBOX_UTMPX.
  Build updates: make change should use top level .config for global settings, add NOSTRIP variable to force skipping strip, and save intermediate flag data in generated/flags.raw and have mkflags.c error message point to that.
  Menuconfig option for musl-libc pretending mmu is just pining for the fijords.
  Static analysis from Hyejin Kim found possible pointer underflow.
  I discovered that the reason SIGINT causes a reboot on sysvinit is that it's how the kernel signals that ctrl-alt-delete has been pressed; thus, setting it as the signal for reboot prevents ctrlaltdel scripts from working. SIGTERM is what Busybox uses, so we might as well be compatible.
  Test for human_readable()
  Kylie McClain pointed out that env should clear variables with NAME= by itself.
  Another Android roadmap update.
  Fix ionice default class.