- Copy stable/10@296371 to releng/10.3 in preparation for 10.3-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.3.
- Update default pkg(8) configuration to use the quarterly branch.

Approved by: re (implicit)

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

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

Fix warnings and style(9) issues.
Set WARNS to 6.

MFC after: 1 week

Remove broken attempt to compile libc's malloc source directly; this
allows this tool to compile again. Albeit, now to test a new malloc
implementation one has to install the new libc which may have bad
consequences (i.e. if the new malloc implementation were buggy).

Add logic to workaround malloc's current behaviour of returning an
invalid non-NULL pointer for 0 byte allocation requests; this prevents the
tool from coring during the NOPS loop.

Add $FreeBSD$ tags.

Update this to match my version.