Fix setup on devices without printflags

Instead of running printflags directly, which on devices that do not
have the binary hangs indefinitely, run "sh -c printflags".

printflags is in the default base_system.mk but some OEMs may strip it
out. sh is much less likely to be removed.

Bug: 379183423
Test: atest
Change-Id: I66af42b2cfbf5cb427c740ef710d8eb3d1d7f1ef
1 file changed