Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Use .PATH instead of VPATH.

Reviewed by: gnn,rwatson

Disable several instances instances of clang's -Wself-assign warning.
All of these are harmless, and are in fact used to shut up warnings from
lint.

While here, remove -Wno-missing-prototypes from the xfs module
Makefile, as I could not reproduce those warnings either with gcc or
clang.

MFC after: 1 week

Merge Neterion if_nxge driver version 2.0.9.11230 with the following
changes:

01 - Enhanced LRO:
LRO feature is extended to support multi-buffer mode. Previously,
Ethernet frames received in contiguous buffers were offloaded.
Now, frames received in multiple non-contiguous buffers can be
offloaded, as well. The driver now supports LRO for jumbo frames.

02 - Locks Optimization:
The driver code was re-organized to limit the use of locks.
Moreover, lock contention was reduced by replacing wait locks
with try locks.

03 - Code Optimization:
The driver code was re-factored to eliminate some memcpy
operations. Fast path loops were optimized.

04 - Tag Creations:
Physical Buffer Tags are now optimized based upon frame size.
For better performance, Physical Memory Maps are now re-used.

05 - Configuration:
Features such as TSO, LRO, and Interrupt Mode can be configured
either at load or at run time. Rx buffer mode (mode 1 or mode 2)
can be configured at load time through kenv.

06 - Driver Statistics:
Run time statistics are enhanced to provide better visibility
into the driver performance.

07 - Bug Fixes:
The driver contains fixes for the problems discovered and
reported since last submission.

08 - MSI support:
Added Message Signaled Interrupt feature which currently uses 1
message.

09 Removed feature:
Rx 3 buffer mode feature has been removed. Driver now supports 1,
2 and 5 buffer modes of which 2 and 5 buffer modes can be used
for header separation.

10 Compiler warning:
Fixed compiler warning when compiled for 32 bit system.

11 Copyright notice:
Source files are updated with the proper copyright notice.

MFC after: 3 days
Submitted by: Alicia Pena <Alicia dot Pena at neterion dot com>,
Muhammad Shafiq <Muhammad dot Shafiq at neterion dot com>

Neterion Xframe 10GbE Server/Storage adapter driver.

The nxge driver provides support for Neterion Xframe-I and Xframe-II
adapters. The driver supports TCP Segmentation Offload (TSO/LSO),
Jumbo frames (5 buffer mode), Header separation (2 and 3 Receive
buffer modes), VLAN, and Promiscuous mode.

Submitted by: Neterion
Reviewed by: rwatson
Approved by: re (kensmith)