Don't use non-portable integer types like __u32
uspace: ensure declaration of pthread_t is available

.. it's used below
Get rid of indirect inclusion of rtapi_errno.h
Don't use <linux/*.h>, <asm/*.h> blindly

.. as there's no guarantee that exists on all platforms.  It's OK if we
somehow know we're in linux (e.g., compiling a kernel module and not for
sim), but otherwise it's a no-no.
Don't use errno constants that aren't portable

Nothing was directly testing for these errno values.

In one case, use EAGAIN since it also expresses the intent (the thing
can't be put or get right now without blocking).

In another case, use EFAULT since it's an out-of-range access situation.
Drop support for kernels below 2.6.14

Per wiki MinimumSoftwareVersions, the oldest place we contemplate
building 2.7 has 2.6.32 (Ubuntu Lucid); even Ubuntu Hardy
has 2.6.24.

This also fixes build errors encountered on debian kfreebsd.
Avoid printf error due to size of semaphore key type

this type is not necessarily any particular width, so this is the
safe way to get it printed.
Don't use nonportable linux socket semantics

Instead, put the rtapi fifo in the home directory (or use RTAPI_FIFO_PATH
from the environment if specified).
platform-is-supported: "arch" has components "os" and "cpu", consider both

On Debian distributions running the Linux kernel, "DEB_HOST_ARCH"
is the same as "DEB_HOST_ARCH_CPU" (the Linux kernel is implied).
But on Debian kFreeBSD, DEB_HOST_ARCH includes both DEB_HOST_ARCH_OS
and DEB_HOST_ARCH_CPU.  This commit lets platform-is-supported consider
both components of the arch.

2.6 (this version) requires DEB_HOST_ARCH_OS to be "linux".
Merge remote-tracking branch 'origin/2.6'

Conflicts:
	scripts/platform-is-supported