MFC r302174

Fix "sysctl vm.vmtotal" output on machines with > 2TB virtual memory

sbin/sysctl/sysctl.c
Fix integer overflows in printf format strings

PR: 199673

MFC: 288984

Only print the errno string in case sysctl(3) does not file with ENOENT
This reduces the noise in error reporing from sysctl(8):

Before:
$ sysctl bla=something
sysctl: unknown oid 'bla': No such file or directory

After:
$ sysctl bla=something
sysctl: unknown oid 'bla'

Sponsored by: Gandi.net

Trim spaces at the end of the buffer before trying to convert it to an oid

This allows to write entries in sysctl.conf with spaces before the '=' like
kern.ipc.shmmax = 9663676416

Sponsored by: Gandi.net

MFC r272044:

Constify a parameter of name2oid. No functional change.

MFC 270828,271487,271495:
Add sysctls to export the BIOS SMAP and EFI memory maps along with
handlers in the sysctl(8) binary to format them.

MFC r267960:
Don't hide zero-length strings when doing sysctl listings.

MFC r258659:

Fix warnings to not append "No error: 0".

Sponsored by: The FreeBSD Foundation

MFC r272044:

Constify a parameter of name2oid. No functional change.

MFC 270828,271487,271495:
Add sysctls to export the BIOS SMAP and EFI memory maps along with
handlers in the sysctl(8) binary to format them.

MFC r267960:
Don't hide zero-length strings when doing sysctl listings.

MFC r258659:

Fix warnings to not append "No error: 0".

Sponsored by: The FreeBSD Foundation