awk: rand() could return 1.0, fix this - should be in [0,1)

While at it, make it finer-grained (63 bits of randomness)

function                                             old     new   delta
evaluate                                            3303    3336     +33
.rodata                                           104107  104111      +4
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 37/0)               Total: 37 bytes

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