busybox

libbb: Use return value from is_prefixed_with()

add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-5 (-5)
Function                                     old     new   delta
skip_dev_pfx                                  30      25      -5
Total: Before=779966, After=779961, chg -0.00%

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>