Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r260102:

Similar to r260020, only use -fms-extensions with gcc, for all other
modules which require this flag to compile. Use a GCC_MS_EXTENSIONS
variable, defined in kern.pre.mk, which can be used to easily supply the
flag (or not), depending on the compiler type.

MFC r260322:

In addition to r260102, also define GCC_MS_EXTENSIONS in bsd.sys.mk,
since kernel module builds do not use kern.pre.mk.

Revert MFC of r260102 for now, until I can merge the required fix from
head. This should fix building modules which require -fms-extensions to
compile them with gcc.

MFC r260102:

Similar to r260020, only use -fms-extensions with gcc, for all other
modules which require this flag to compile. Use a GCC_MS_EXTENSIONS
variable, defined in kern.pre.mk, which can be used to easily supply the
flag (or not), depending on the compiler type.

MFC 233040,233198,233870,234183:
Add OFED and the associated options and drivers to x86 LINT builds:
- Fix build with INET6 disabled.
- Fix build of OFED bits with debugging options enabled.
- Fix build on i386.
- Mark 'sdp' as requiring 'inet'.
- Always include "opt_inet.h" and "opt_inet6.h" and modify the IB
driver Makefiles to honor WITH/WITHOUT_INET/INET6/_SUPPORT options
to determine what should be enabled during a module build.
- Fix the mlxen(4) driver and the core IB code to compile without
if INET is disabled (including when both INET and INET6 are disabled).

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

- Merge in OFED 1.5.3 from projects/ofed/head