recovery: fix building with pointer-to-int errors turned on

Use intptr_t/uintptr_t to cast between pointer and int to allow
building with -Werror=pointer-to-int-cast and
Werror=int-to-pointer-cast turned on.

Cast to char* instead of unsigned int for pointer arithmetic.

Conflicts:
	minui/graphics.c

Change-Id: Ia862306fdcca53866b330e8cf726f3d62f2248a0
add --shutdown_after option to recovery

The "--shutdown_after" option causes recovery to power down the device
on completion rather than rebooting.

Removes the last vestiges of the "--previous_runs" argument, which
doesn't seem to be used for anything.

Conflicts:
	recovery.c

Change-Id: I465eda2ef59d367e2b1c79a8dc69831263c69a4d