Document copyright situation and select default license

This patch is not intended to change the copyright or license
situation of any of the original code.

Documentation is provided that identifies the various licenses we
have in the source tree.

The default license for new items after the 'Initial commit' merge is
corrected to match the majority license already in use. This is the
license we recommend all new code use. This corrects a mistake I made
in the 'Unified CMake build system' patch which selected the wrong
license file.

Also provide specific guidance on how the 18 different COPYING files
and per-file copyright headers are intended to be interpreted
within the merged tree.

Fixes: 8d4ebd8 ("Unified CMake build system")
Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>

COPYING.BSD_FB

@@ -0,0 +1,22 @@
+		   OpenIB.org BSD license (FreeBSD Variant)
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+  - Redistributions of source code must retain the above copyright notice,
+    this list of conditions and the following disclaimer.
+
+  - Redistributions in binary form must reproduce the above copyright notice,
+    this list of conditions and the following disclaimer in the documentation
+    and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

COPYING.BSD_MIT

@@ -0,0 +1,20 @@
+		     OpenIB.org BSD license (MIT variant)
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+  - Redistributions of source code must retain the above copyright notice,
+    this list of conditions and the following disclaimer.
+
+  - Redistributions in binary form must reproduce the above copyright notice,
+    this list of conditions and the following disclaimer in the documentation
+    and/or other materials provided with the distribution.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+

COPYING.md

@@ -0,0 +1,75 @@
+# Default Dual License
+
+Unless otherwise stated this software is available to you under a choice of
+one of two licenses.  You may choose to be licensed under the terms of the the
+OpenIB.org BSD (MIT variant) license (see COPYING.BSD_MIT) or the GNU General
+Public License (GPL) Version 2 (see COPYING.GPL2), both included in this
+package.
+
+Files marked 'See COPYING file' are licensed under the above Dual License.
+
+# Other Options
+
+Individual source files may use a license different from the above Defaul Dual
+License. If a license is declared in the file then it supersedes the Default
+License.
+
+If a directory contains a COPYING file then the License from that file becomes
+the Default License for files in that directory and below.
+
+# Copyright Holders
+
+Refer to individual files for information on the copyright holders.
+
+# License Catalog (Informative, Non Binding)
+
+## Utilities
+
+Utility source code that may be linked into any binary are available under
+several licenses:
+
+   - MIT license (see ccan/LICENSE.BSD-MIT)
+   - Creative Commons CC0 1.0 Universal License (see ccan/LICENSE.CC0)
+
+## Providers
+
+The following providers use a different license than the Default Dual
+License. Refer to files in each directory for details.
+
+cxbg4
+: A combination of the
+    - Default Dual License
+    - cxgb4/src/queue.h: BSD 3 clause license.
+
+hfi1verbs
+: Dual License: GPLv2 or Intel 3 clause BSD license
+
+ipathverbs
+: Dual License: GPLv2 or PathScale BSD Patent license
+
+ocrdma
+: Dual License: GPLv2 or OpenIB.org BSD (FreeBSD variant), See COPYING.BSD_FB
+
+rxe
+: A combination of the
+    - Default Dual License
+    - GPLv2 or PathScale BSD Patent license
+
+## Libraries
+
+All library compilable source code (.c and .h files) are available under the
+Default Dual License.
+
+Unmarked ancillary files may be available under a Dual License: GPLv2 or
+OpenIB.org BSD (FreeBSD variant).
+
+## Tools (iwpmd, srp_deamon, ibacm)
+
+All compilable source code (.c and .h files) are available under the Default
+Dual License.
+
+Unmarked ancillary files may be available under a Dual License: GPLv2 or
+OpenIB.org BSD (FreeBSD variant).
+
+srp_daemon/srp_daemon/srp_daemon.sh: Any one of the GPLv2, a 2 clause BSD
+license or the CPLv1.