MFC r328598 (by emaste@):

makesyscalls: permit a range of syscall numbers for UNIMPL

Some ABIs have large gaps in syscall numbers. Allow gaps to be filled
as ranges of UNIMPL, with an entry like:

248-1023 AUE_NULL UNIMPL unimplemented

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 r303755:

Still provide freebsd10_* symbols from libc for COMPAT10.

Approved by: re (gjb)