sys: Remove ancient SCCS tags.

Remove ancient SCCS tags from the tree, automated scripting, with two
minor fixup to keep things compiling. All the common forms in the tree
were removed with a perl script.

Sponsored by: Netflix

sys: Remove $FreeBSD$: one-line .h pattern

Remove /^\s*\*+\s*\$FreeBSD\$.*$\n/

Reduce code duplication in machine/_types.h

Many of these typedefs are the same across all architectures or can
be set based on an architecture-independent compiler-provided macro
(e.g. __SIZEOF_SIZE_T__). These macros have been available since GCC 4.6
and Clang sometime before 3.0 (godbolt.org does not have any older clang
versions installed).

I originally considered using the compiler-provided `__FOO_TYPE__` directly.
However, in order to do so we have to check that those match the previous
typedef exactly (not just that they have the same size) since any change
would be an ABI break. For example, changing `long` to `long long` results
in different C++ name mangling. Additionally, Clang and GCC disagree on
the underlying type for some of (u)int*_fast_t types, so this change
only moves the definitions that are identical across all architectures
and does not touch those types.

This de-deduplication will allow us to have a smaller diff downstream in
CheriBSD: we only have to only change the (u)intptr_t definition in
sys/_types.h in CheriBSD instead of having to change machine/_types.h for
all CHERI-enabled architectures (currently RISC-V, AArch64 and MIPS).

Reviewed By: imp, kib
Differential Revision: https://reviews.freebsd.org/D29895

Do not include float interfaces when using libsa.

We don't support float in the boot loaders, so don't include
interfaces for float or double in systems headers. In addition, take
the unusual step of spiking double and float to prevent any more
accidental seepage.

Move __va_list and related defines to sys/sys/_types.h

__va_list and related defines are identical in all the
ARCH/include/_types.h files. Move them to sys/sys/_types.h

Sponsored by: Netflix

Define the vm_ooffset_t and vm_pindex_t types as machine-independend.

The types are for the byte offset and page index in vm object. They
are similar to off_t, which is defined as 64bit MI integer. Using MI
definitions will allow to provide consistent MD values of vm
object-related maximum sizes.

Reviewed by: alc
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

Import RISC-V machine headers. This is a minimal set required to compile
kernel and userland.

Reviewed by: andrew, imp, kib
Sponsored by: DARPA, AFRL
Sponsored by: HEIF5
Differential Revision: https://reviews.freebsd.org/D4554