Add input file to generate uninstall rule

Add the file proposed by the CMake FAQ to generate an uninstall rule in the build directory. Each project which wants to use it must duplicate the piece of code given as a comment in the file.

modules/cmake_uninstall.cmake.in

+###
+#
+# @copyright (c) 2012-2020 Inria. All rights reserved.
+# @copyright (c) 2012-2020 Bordeaux INP, CNRS (LaBRI UMR 5800), Inria,
+#                          Univ. Bordeaux. All rights reserved.
+#
+###
+#
+#  @file cmake_uninstall.cmake.in
+#
+#  @project MORSE
+#  MORSE is a software package provided by:
+#     Inria Bordeaux - Sud-Ouest,
+#     Univ. of Tennessee,
+#     King Abdullah Univesity of Science and Technology
+#     Univ. of California Berkeley,
+#     Univ. of Colorado Denver.
+#
+#  @version 0.9.0
+#  @author Mathieu Faverge
+#  @date 13-05-2015
+#
+# This file is a copy-paste of the file propose by the cmake FAQ
+# https://gitlab.kitware.com/cmake/community/-/wikis/FAQ#can-i-do-make-uninstall-with-cmake
+#
+# If you want to use this file in your project, add the following
+# block at the top-level CMakeLists.txt
+#
+# # uninstall target
+# if(NOT TARGET uninstall)
+#     configure_file(
+#         "${MORSE_CMAKE_MODULE_PATH}/cmake_uninstall.cmake.in"
+#         "${CMAKE_CURRENT_BINARY_DIR}/cmake_uninstall.cmake"
+#         IMMEDIATE @ONLY)
+# 
+#     add_custom_target(uninstall
+#         COMMAND ${CMAKE_COMMAND} -P ${CMAKE_CURRENT_BINARY_DIR}/cmake_uninstall.cmake)
+# endif()
+#
+###
+if(NOT EXISTS "@CMAKE_BINARY_DIR@/install_manifest.txt")
+  message(FATAL_ERROR "Cannot find install manifest: @CMAKE_BINARY_DIR@/install_manifest.txt")
+endif(NOT EXISTS "@CMAKE_BINARY_DIR@/install_manifest.txt")
+
+file(READ "@CMAKE_BINARY_DIR@/install_manifest.txt" files)
+string(REGEX REPLACE "\n" ";" files "${files}")
+foreach(file ${files})
+  message(STATUS "Uninstalling $ENV{DESTDIR}${file}")
+  if(IS_SYMLINK "$ENV{DESTDIR}${file}" OR EXISTS "$ENV{DESTDIR}${file}")
+    exec_program(
+      "@CMAKE_COMMAND@" ARGS "-E remove \"$ENV{DESTDIR}${file}\""
+      OUTPUT_VARIABLE rm_out
+      RETURN_VALUE rm_retval
+      )
+    if(NOT "${rm_retval}" STREQUAL 0)
+      message(FATAL_ERROR "Problem when removing $ENV{DESTDIR}${file}")
+    endif(NOT "${rm_retval}" STREQUAL 0)
+  else(IS_SYMLINK "$ENV{DESTDIR}${file}" OR EXISTS "$ENV{DESTDIR}${file}")
+    message(STATUS "File $ENV{DESTDIR}${file} does not exist.")
+  endif(IS_SYMLINK "$ENV{DESTDIR}${file}" OR EXISTS "$ENV{DESTDIR}${file}")
+endforeach(file)