- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Unbreak the build for arm and powerpc.

Pointy hat to yours truly.

Make several changes to the way printf handles hex floating point (%a):

1. Previously, printing the number 1.0 could produce 0x1p+0, 0x2p-1,
0x4p-2, or 0x8p-3, depending on what happened to be convenient. This
meant that printing a value as a double and printing the same value
as a long double could produce different (but equivalent) results.
The change is to always make the leading digit a 1, unless the
number is 0. This solves the aforementioned problem and has
several other advantages.

2. Use the FPU to do rounding. This is far simpler and more portable
than manipulating the bits, and it fixes an obsure round-to-even
bug. It also raises the exceptions now required by IEEE 754R.
The drawbacks are that it is usually slightly slower, and it makes
printf less effective as a debugging tool when the FPU is hosed
(e.g., due to a buggy softfloat implementation).

3. On i386, twiddle the rounding precision so that (2) works properly
for long doubles.

4. Make several simplifications that are now possible due to (2).

5. Split __hldtoa() into a separate file.

Thanks to remko for access to a sparc64 box for testing.

Fix a rounding error.

Reported by: Bruno Haible

Fix rounding of 0xf for hex fp formats.

PR: 90333

Cut out the gordian handling of subnormals by bit fiddling, and
instead use the FPU to convert subnormals to normals. (NB: Further
simplification is possible, such as using the FPU for the rounding
step.)

This fixes a bug reported by stefanf where long double subnormals in
the Intel 80-bit format would be output with one fewer digit than
necessary when the default precision was used.

Updated manh shift constant type to 'ULL' for PPC to fix
shift-too-large compile error

reviewed by: das

Implement __hdtoa() and __hldtoa() and enable printf() support for %a
and %A, which print floating-point numbers in hexadecimal.