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/

powerpc: clean up empty lines in .c and .h files

[PowerPC] kernel ifunc support for powerpc*, fix ppc64 relocation oddities.

This is a general cleanup of the relocatable kernel support on powerpc,
needed to enable kernel ifuncs.

* Fix some relocatable issues in the kernel linker, and change to using
a RELOCATABLE_KERNEL #define instead of #ifdef __powerpc__ for parts that
other platforms can use in the future if they wish to have ET_DYN kernels.

* Get rid of the DB_STOFFS hack now that the kernel is relocated to the DMAP
properly across the board on powerpc64.

* Add powerpc64 and powerpc32 ifunc functionality.

* Allow AIM64 virtual mode OF kernels to run from the DMAP like other AIM64
by implementing a virtual mode restart. This fixes the runtime address on
PowerMac G5.

* Fix symbol relocation problems on post-relocation kernels by relocating
the symbol table.

* Add an undocumented method for supplying kernel symbols on powernv and
other powerpc machines using linux-style kernel/initrd loading -- If
you pass the kernel in as the initrd as well, the copy resident in initrd
will be used as a source for symbols when initializing the debugger.
This method is subject to removal once we have a better way of doing this.

Approved by: jhibbits
Relnotes: yes
Sponsored by: Tag1 Consulting, Inc.
Differential Revision: https://reviews.freebsd.org/D23156

[PPC64] Fix ofw_initrd

Before this change, OFW initrd (as md) handling code was simulating an ofwbus
device. But as there isn't really a Device Tree (DT) node representing OFW
initrd (it is specified in 2 properties under /chosen), its driver was in fact
stealing other driver's DT node. This was noticed after MD_ROOT_MEM became
default and QEMU's USB keyboard stopped working under VNC.

This change consists in simplifying the process of detection and mapping of
initrd memory, turning it into a simple startup step, instead of trying to
simulate a device.

Reviewed by: jhibbits
Differential Revision: https://reviews.freebsd.org/D20553

ofw: Load initrd file

This is an OFW initrd module that would load the initrd from device tree
parameters and give the to the md driver.

With this patch, it is possible to pass a rootfs image through kexec in PowerNV
mode (powerpc64). In order to user it, you should set the MD_ROOT_MEM option in
your kernel configuration.

Reviewed by: jhibbits
Approved by: jhibbits (mentor)
Differential Revision: https://reviews.freebsd.org/D15705