1. Fix the results for negative subnormals by ignoring the signal when
normalizing the value.
2. Fix the output when the high part is a power of 2 and the low part
is a nonzero number with opposite sign. This fix is based on commit
380bd0fd2418f8988217de950f8b8ff18af0cb2b.
After applying this patch, logbl() tests pass cleanly on POWER >= 7.
Tested on powerpc, powerpc64 and powerpc64le
[BZ #21280]
* sysdeps/powerpc/power7/fpu/s_logbl.c (__logbl): Ignore the
signal of subnormals and adjust the exponent of power of 2 down
when low part has opposite sign.
c064f6a613