[PATCH] Fix the inaccuracy of j0f (BZ 14469) and y0f (BZ 14471) [v2]

[Paul Zimmermann]

       Dear Adhemerval,

> So if I understand correctly, you patch increase the ulps for non-default
> rounding for this specific inputs? If it were the case, could be fix it
> as well? 

I guess the previous code already had an error > 9 ulps on this specific
input:

Failure: Test: j0_downward (0x3.17bcfcp+4)
Result:
 is:          1.1670220923447945e-04   0x1.e97c0b0296dc8p-14
 should be:   1.1670220923447976e-04   0x1.e97c0b0296ddfp-14
 difference:  3.1170812458958252e-19   0x1.7000000000000p-62
 ulp       :  23.0000
 max.ulp   :  2.0000

However on my machine I have an error of only 9 ulps for that input.
Maybe your machine doesn't have fma? Maybe I should develop my code
on a machine without fma, assuming the errors will be smaller with fma.

Paul