*: optimize most of isXXXXX() macros

   text    data     bss     dec     hex filename
 824164     453    6812  831429   cafc5 busybox_old
 823730     453    6812  830995   cae13 busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
7 files changed