bug(printf): %.a with hex large values lead to output mismatch between gnu and uu

[HackingRepo]

Hi, uutils mainteners

we confirmed that when testing printf here is how can be reproduced

relunsec@relunsec:~/software/coreutils/target/debug$ ./printf %.a 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
0x1p+216relunsec@relunsec:~/software/coreutils/target/debug$ 
relunsec@relunsec:~/software/coreutils/target/debug$ gnuprintf %.a 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
0x8p+213relunsec@relunsec:~/software/coreutils/target/debug$ 

as you can see there was a big difference in the output