- 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

Fix handling of subnormals on i386/ia64/amd64.

PR: 85080

In scanf, round according to the current rounding mode.

Use an intermediate pointer to avoid a strict aliasing warning.

Note that ULong in this code is actually defined as an unsigned integer across
all arches so that the gdtoa() function always processes 32 bit data
despite the unfortunate naming of "ULong".

Fix a bug that caused long double subnormals to be printed
incorrectly on architectures without an explicit normalization
bit (sparc64, powerpc).

Add __ldtoa(), a wrapper around gdtoa() to make it look like dtoa().
In support of this, add some MD macros to assist in converting long
doubles to the format expected by gdtoa().

Reviewed by: silence on standards@