MFC r263778:

Add a SUBDIR_PARALLEL option to bsd.subdir.mk, to allow make to process
all the SUBDIR entries in parallel, instead of serially.  Apply this
option to a selected number of Makefiles, which can greatly speed up the
build on multi-core machines, when using make -j.

This can be extended to more Makefiles later on, whenever they are
verified to work correctly with parallel building.

I tested this on a 24-core machine, with make -j48 buildworld (N = 6):

		before    stddev       after    stddev
		=======   ======       =======  ======
real time        1741.1     16.5         959.8     2.7
user time       12468.7     16.4       14393.0    16.8
sys  time        1825.0     54.8        2110.6    22.8

(user+sys)/real     8.2                   17.1

E.g. the build was approximately 45% faster in real time.  On machines
with less cores, or with lower -j settings, the speedup will not be as
impressive.  But at least you can now almost max out a machine with
buildworld!

Submitted by:	jilles

MFC r263833:

Enable parallel building for gnu/usr.bin and usr.bin/clang too.
MFC r264238:

For GNU as, add two missing modes for each of the fcomip and fucomip
instructions.  Partially obtained from OpenBSD by Pedro Giffuni, while I
added the fcomip variants.

Apparently this should help with compiling certain variants of WebKit.
MFC r263429

Fix kern/187712: config(8) does not respect KERNCONFDIR.
The impact of this bug is that you cannot build a kernel if both of the
following are true:
1) The kernel config file is in a non-default location
2) The kernel config file uses the "include" statement from config(5).

usr.sbin/config/main.c
usr.sbin/config/config.8
usr.sbin/config/config.h
usr.sbin/config/lang.l
	Added a "-I path" option to config(8).  By analogy to cc(1), it adds
	an extra path in which the "include" statement will search for
	files.

Makefile.inc1
        Pass "-I ${KERNCONFDIR}" to config(8).
Merge r264084: make the Dresden Elektronik "USB Level Shifter Low Cost"
known to the FTDI driver.
MFC:	r261037, r264278

Merge OpenSSL 1.0.1f and 1.0.1g.
MFC r263879:

  Add `-S' to display syscall numbers in the output as well.
MFC r263459: MFV 263436-263438:

3947 zpool(1M) references nonexistent zfs-features(5)
4540 zpool(1M) man page doesn't describe "readonly" property
3948 zfs sync=default is not accepted
4611 zfs(1M) still mentions 'send -r' in synopsis
4415 zpool(1M) man page missing "import -m" description
4570 Document dedupditto pool property
4572 Dedup-related documentation additions for zpool and zdb.
1371 Add -D option description to zpool(1M) manpage
4571 Add documentation for -T and interval to "zpool list"
MFC r263889 (MFV r263887):

3993 zpool(1M) and zfs(1M) should support -p for "list" and "get"
4700 "zpool get" doesn't support -H or -o options
MFC r264294:
Fix for infinite XHCI reset loops when the set address USB request fails.