MFC 313999: Consolidate statements to initialize files.

Previously, the first lines of various generated files from system call
tables were generated in two sections. Some of the initialization was
done in BEGIN, and the rest was done when the first line was encountered.
The main reason for this split before r313564 was that most of the
initialization done in the second section depended on the $FreeBSD$ tag
extracted from the system call table. Now that the $FreeBSD$ tag is no
longer used, consolidate all of the file initialization in the BEGIN
section.

This change was tested by confirming that the content of generated files
did not change.

MFC 313564:
Drop the "created from" line from files generated by makesyscalls.sh.

This information is less useful when the generated files are included in
source control along with the source. If needed it can be reconstructed
from the $FreeBSD$ tag in the generated file. Removing this information
from the generated output permits committing the generated files along
with the change to the system call master list without having inconsistent
metadata in the generated files.

Regenerate the affected files along with the MFC.

MFC r307522: makesyscalls.sh: remove trailing space on the "created from" line

In r10905 and r10906 makesyscalls was modified to avoid emitting a
literal $Id$ string in the generated file, with:

gsub("[$]Id: ", "", $0)
gsub(" [$]", "", $0)

Then r11294 added some functionality and also tried to address the $Id$
problem in a different way, by removing every $:

sed -e 's/\$//g ...

This rendered the gsub infeffective. The gsub was later updated to
track the $Id$ -> $FreeBSD$ switch, even though it did not do anything.

Revert the addition of the s/\$//g, and update the gsub to keep the
resulting format the same.

MFC 289769,289822,290143,290144:
Rename remaining linux32 symbols from linux_* to linux32_*.

289769:
Rename remaining linux32 symbols such as linux_sysent[] and
linux_syscallnames[] from linux_* to linux32_* to avoid conflicts with
linux64.ko. While here, add support for linux64 binaries to systrace.
- Update NOPROTO entries in amd64/linux/syscalls.master to match the
main table to fix systrace build.
- Add a special case for union l_semun arguments to the systrace
generation.
- The systrace_linux32 module now only builds the systrace_linux32.ko.
module on amd64.
- Add a new systrace_linux module that builds on both i386 and amd64.
For i386 it builds the existing systrace_linux.ko. For amd64 it
builds a systrace_linux.ko for 64-bit binaries.

289822:
Fix build for the KTR-enabled kernels.

290143:
Fix build with DEBUG defined.

290144:
Update for LINUX32 rename. The assembler didn't complain about undefined
symbols but just used 0 after the rename.

MFC r256643: makesyscalls.sh: Error on failure to open specified config file

MFC r259438 by pjd: Fix syscalls that can be loaded as kernel modules

They were not given the flag allowing to call them from capability
mode sandbox.

And regenerate init_sysent.c

Sponsored by: The FreeBSD Foundation

MFC r256643: makesyscalls.sh: Error on failure to open specified config file

MFC r259438 by pjd: Fix syscalls that can be loaded as kernel modules

They were not given the flag allowing to call them from capability
mode sandbox.

And regenerate init_sysent.c

Sponsored by: The FreeBSD Foundation