sys: Automated cleanup of cdefs and other formatting

Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.

Remove /^#if.*\n#endif.*\n#include\s+<sys/cdefs.h>.*\n/
Remove /\n+#include\s+<sys/cdefs.h>.*\n+#if.*\n#endif.*\n+/
Remove /\n+#if.*\n#endif.*\n+/
Remove /^#if.*\n#endif.*\n/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/types.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/param.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/capsicum.h>/

Sponsored by: Netflix

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

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

xen/intr: move interrupt allocation/release to architecture

Simply moving the interrupt allocation and release functions into files
which belong to the architecture. Since x86 interrupt handling is quite
distinct from other architectures, this is a crucial necessary step.

Identifying the border between x86 and architecture-independent is
actually quite tricky. Similarly, getting the prototypes for the
border right is also quite tricky.

Inspired by the work of Julien Grall <julien@xen.org>,
2015-10-20 09:14:56, but heavily adjusted.

Reviewed by: royger
Differential Revision: https://reviews.freebsd.org/D30936

xen/intr: move x86 PIC interface to xen_arch_intr.c, introduce wrappers

The x86 PIC interface is very much x86-specific and not used by other
architectures. Since most of xen_intr.c can be shared with other
architectures, the PIC interface needs to be broken off.

Introduce wrappers for calls into the architecture-dependent interrupt
layer. All architectures need roughly the same functionality, but the
interface is slightly different between architectures. Due to the
wrappers being so thin, all of them are implemented as inline in
arch-intr.h.

The original implementation was done by Julien Grall in 2015, but this
has required major updating.

Removal of PVHv1 meant substantial portions disappeared. The original
implementation took care of moving interrupt allocation to
xen_arch_intr.c, but this has required massive rework and was broken
off.

In the original implementation the wrappers were normal functions. Some
had empty stubs in xen_intr.c and were removed.

Reviewed by: royger
Submitted by: Elliott Mitchell <ehem+freebsd@m5p.com>
Original implementation: Julien Grall <julien@xen.org>, 2015-10-20 09:14:56
Differential Revision: https://reviews.freebsd.org/D30909

xen/intr: adjust xen_intr_handle_upcall() to match driver filter

xen_intr_handle_upcall() has two interfaces. It needs to be called by
the x86 assembly code invoked by the APIC. Second, it needs to be called
as a driver_filter_t for the XenPCI code and for architectures besides
x86.

Unfortunately the driver_filter_t interface was implemented as a wrapper
around the x86-APIC interface. Now create a simple wrapper for the
x86-APIC code, which calls an architecture-independent
xen_intr_handle_upcall().

When called via intr_event_handle(), driver_filter_t functions expect
preemption to be disabled. This removes the need for
critical_enter()/critical_exit() when called this way.

The lapic_eoi() call is only needed on x86 in some cases when invoked
directly as an APIC vector handler.

Additionally driver_filter_t functions have no need to handle interrupt
counters. The intrcnt_add() calling function was reworked to match the
current situation. intrcnt_add() is now only called via one path.

The increment/decrement of curthread->td_intr_nesting_level had
previously been left out. Appears this was mostly harmless, but this
was noticed during implementation and has been added.

CONFIG_X86 is a leftover from use with Linux. While the barrier isn't
needed for FreeBSD on x86, it will be needed for FreeBSD on other
architectures.

Copyright note. xen_intr_intrcnt_add() was introduced at 76acc41fb7c7
by Justin T. Gibbs. xen_intrcnt_init() was introduced at fd036deac1695
by John Baldwin.

sys/x86/xen/xen_arch_intr.c was originally created by Julien Grall in
2015 for the purpose of holding the x86 interrupt interface. Later it
was found xen_intr_handle_upcall() was better earlier, and the x86
interrupt interface better later. As such the filename and header list
belong to Julien Grall, but what those were created for is later.

Reviewed by: royger
Differential Revision: https://reviews.freebsd.org/D30006