Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

Fix ibnd_* manpages sources

Some ibnd_* manpages source other manpages from a `man3/` directory when it
should reference the pages in the current directory.

Instead of modifying contributing sources and using `.so` (discouraged by
mandoc(1)) use MLINKS in the proper Makefile and do not install the affected
manpages.

PR: 237693
Reported by: wosch@FreeBSD.org
Reviewed by: gbe@ (mentor) yuripv@
Approved by: gbe@ (mentor) yuripv@
Differential Revision: https://reviews.freebsd.org/D28727

Remove remaining uses of ${COMPILER_FEATURES:Mc++11}

All supported compilers have C++11 support so these checks can be replaced
with MK_CXX guards.
See also https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=252759

PR: 252759
Reviewed By: emaste
Differential Revision: https://reviews.freebsd.org/D28234

Rework CXXSTD setting via r345708

This change allows the user to once again override the C++ standard, restoring
high-level pre-r345708 behavior.

This also unbreaks building lib/ofed/libibnetdisc/Makefile with a non-C++11
capable compiler, e.g., g++ 4.2.1, as the library supported being built with
older C++ standards.

MFC after: 2 weeks
MFC with: r345708
Reviewed by: emaste
Reported by: jbeich
Differential Revision: https://reviews.freebsd.org/D19895 (as part of a larger change)

Standardize `-std=c++* as `CXXSTD`

CXXSTD was added as the C++ analogue to CSTD.

CXXSTD defaults to `-std=c++11` with supporting compilers; `-std=gnu++98`,
otherwise for older versions of g++.

This change standardizes the CXXSTD variable, originally added to
googletest.test.inc.mk as part of r345203.

As part of this effort, convert all `CXXFLAGS+= -std=*` calls to use `CXXSTD`.

Notes:

This value is not sanity checked in bsd.sys.mk, however, given the two
most used C++ compilers on FreeBSD (clang++ and g++) support both modes, it is
likely to work with both toolchains. This method will be refined in the future
to support more variants of C++, as not all versions of clang++ and g++ (for
instance) support C++14, C++17, etc.

Any manual appending of `-std=*` to `CXXFLAGS` should be replaced with CXXSTD.
Example:

Before this commit:
```
CXXFLAGS+= -std=c++14
```

After this commit:
```
CXXSTD= c++14
```

Reviewed by: asomers
Approved by: emaste (mentor)
MFC after: 1 month
MFC with: r345203, r345704, r345705
Relnotes: yes
Tested with: make tinderbox
Differential Revision: https://reviews.freebsd.org/D19732

Revert r345706: the third time will be the charm

When a review is closed via Phabricator it updates the patch attached to the
review. I downloaded the raw patch from Phabricator, applied it, and repeated
my mistake from r345704 by accident mixing content from D19732 and D19738.

For my own personal sanity, I will try not to mix reviews like this in the
future.

MFC after: 1 month
MFC with: r345706
Approved by: emaste (mentor, implicit)

Standardize `-std=c++* as `CXXSTD`

CXXSTD was added as the C++ analogue to CSTD.

CXXSTD defaults to `-std=c++11` with supporting compilers; `-std=gnu++98`,
otherwise for older versions of g++.

This change standardizes the CXXSTD variable, originally added to
googletest.test.inc.mk as part of r345203.

As part of this effort, convert all `CXXFLAGS+= -std=*` calls to use `CXXSTD`.

Notes:

This value is not sanity checked in bsd.sys.mk, however, given the two
most used C++ compilers on FreeBSD (clang++ and g++) support both modes, it is
likely to work with both toolchains. This method will be refined in the future
to support more variants of C++, as not all versions of clang++ and g++ (for
instance) support C++14, C++17, etc.

Any manual appending of `-std=*` to `CXXFLAGS` should be replaced with CXXSTD.
Example:

Before this commit:
```
CXXFLAGS+= -std=c++14
```

After this commit:
```
CXXSTD= c++14
```

Reviewed by: asomers
Approved by: emaste (mentor)
MFC after: 1 month
MFC with: r345203, r345704, r345705
Relnotes: yes
Tested with: make tinderbox
Differential Revision: https://reviews.freebsd.org/D19732

Revert r345704

I accidentally committed code from two reviews. I will reintroduce the code to
bsd.progs.mk as part of a separate commit from r345704.

Approved by: emaste (mentor, implicit)
MFC after: 2 months
MFC with: r345704

CXXSTD is the C++ analogue to CSTD.

CXXSTD defaults to `-std=c++11` with supporting compilers; `-std=gnu++98`,
otherwise for older versions of g++.

This change standardizes the CXXSTD variable, originally added to
googletest.test.inc.mk as part of r345203.

As part of this effort, convert all `CXXFLAGS+= -std=*` calls to use `CXXSTD`.

Notes:

This value is not sanity checked in bsd.sys.mk, however, given the two
most used C++ compilers on FreeBSD (clang++ and g++) support both modes, it is
likely to work with both toolchains. This method will be refined in the future
to support more variants of C++, as not all versions of clang++ and g++ (for
instance) support C++14, C++17, etc.

Any manual appending of `-std=*` to `CXXFLAGS` should be replaced with CXXSTD.
Example:

Before this commit:
```
CXXFLAGS+= -std=c++14
```

After this commit:
```
CXXSTD= c++14
```

Reviewed by: asomers
Approved by: emaste (mentor)
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D19732

Rework ofed build.

Aligns the build with the FreeBSD traditional approach to not build in
contrib/, and to track inter-dependencies between libraries.

With help from: bdrewery
Reviewed by: bdrewery, hselasky
Sponsored by: Mellanox Technologies
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D15648