20260911
  Update more files in gdtoa/test to reflect numbers added to the
gdtoa/test/testnos file in the changes of 20111102.
  Add -lm to some rules in gdtoa/test/makefile (need for fegetround
on some systems).
  Added to gdtoa/README:
Addition (20260911) on double rounmding, based only on experience with
a Linux machine with an Intel x86_64 CPU...  Use of 80-bit arithmetic
rounded to bits (long double to double) may give wrong results due to
double rounding.  Compilations by "gcc -m32" and "clang -m32" (to use
32-bit addressing) have this property.  Compilation by
"gcc -m32 -mfpmath=sse" uses 32-bit addressing but avoids double
rounding.  The (current) default addressing for both gcc and clang is
-m64 (64-bit addressing) and uses SSE instructions, avoiding double
rounding.  An input to strtod subject to double rounding when 80-bit
arithmetic is rounded to 64 bits is 8.3e26 (or the multiplication
83e13 times 1e12).