CMake: add FindSWIG.cmake from CMake 3.5 for swig 3.0 support.

* The FindSWIG.cmake shipped with CMake 3.0 does not yet look for the
  "cmake3.0" binary, this was added shortly after the 3.0 release.

* This file can be removed once the minimum CMake version is 3.1 or greater.

CMakeModules/FindSWIG.cmake

@@ -0,0 +1,96 @@
+#.rst:
+# FindSWIG
+# --------
+#
+# Find SWIG
+#
+# This module finds an installed SWIG.  It sets the following variables:
+#
+# ::
+#
+#   SWIG_FOUND - set to true if SWIG is found
+#   SWIG_DIR - the directory where swig is installed
+#   SWIG_EXECUTABLE - the path to the swig executable
+#   SWIG_VERSION   - the version number of the swig executable
+#
+#
+#
+# The minimum required version of SWIG can be specified using the
+# standard syntax, e.g.  find_package(SWIG 1.1)
+#
+# All information is collected from the SWIG_EXECUTABLE so the version
+# to be found can be changed from the command line by means of setting
+# SWIG_EXECUTABLE
+
+#=============================================================================
+# Copyright 2004-2009 Kitware, Inc.
+# Copyright 2011 Mathieu Malaterre <mathieu.malaterre@gmail.com>
+# Copyright 2014 Sylvain Joubert <joubert.sy@gmail.com>
+#
+# 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.
+#
+# * Neither the names of Kitware, Inc., the Insight Software Consortium,
+#   nor the names of their contributors may be used to endorse or promote
+#   products derived from this software without specific prior written
+#   permission.
+#
+# 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
+# HOLDER 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.
+
+find_program(SWIG_EXECUTABLE NAMES swig3.0 swig2.0 swig)
+
+if(SWIG_EXECUTABLE)
+  execute_process(COMMAND ${SWIG_EXECUTABLE} -swiglib
+    OUTPUT_VARIABLE SWIG_swiglib_output
+    ERROR_VARIABLE SWIG_swiglib_error
+    RESULT_VARIABLE SWIG_swiglib_result)
+
+  if(SWIG_swiglib_result)
+    if(SWIG_FIND_REQUIRED)
+      message(SEND_ERROR "Command \"${SWIG_EXECUTABLE} -swiglib\" failed with output:\n${SWIG_swiglib_error}")
+    else()
+      message(STATUS "Command \"${SWIG_EXECUTABLE} -swiglib\" failed with output:\n${SWIG_swiglib_error}")
+    endif()
+  else()
+    string(REGEX REPLACE "[\n\r]+" ";" SWIG_swiglib_output ${SWIG_swiglib_output})
+    find_path(SWIG_DIR swig.swg PATHS ${SWIG_swiglib_output} NO_CMAKE_FIND_ROOT_PATH)
+    if(SWIG_DIR)
+      set(SWIG_USE_FILE UseSWIG)
+      execute_process(COMMAND ${SWIG_EXECUTABLE} -version
+        OUTPUT_VARIABLE SWIG_version_output
+        ERROR_VARIABLE SWIG_version_output
+        RESULT_VARIABLE SWIG_version_result)
+      if(SWIG_version_result)
+        message(SEND_ERROR "Command \"${SWIG_EXECUTABLE} -version\" failed with output:\n${SWIG_version_output}")
+      else()
+        string(REGEX REPLACE ".*SWIG Version[^0-9.]*\([0-9.]+\).*" "\\1"
+          SWIG_version_output "${SWIG_version_output}")
+        set(SWIG_VERSION ${SWIG_version_output} CACHE STRING "Swig version" FORCE)
+      endif()
+    endif()
+  endif()
+endif()
+
+include(FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(SWIG  REQUIRED_VARS SWIG_EXECUTABLE SWIG_DIR
+                                        VERSION_VAR SWIG_VERSION )
+
+mark_as_advanced(SWIG_DIR SWIG_VERSION)