Add package configuration file

Former-commit-id: 2397ab9df88eeb75abbcda7e57ff95920b59f6a4

shared/cmake/libigl-config.cmake.in

@@ -0,0 +1,4 @@
+@PACKAGE_INIT@
+
+include(${CMAKE_CURRENT_LIST_DIR}/libigl-export.cmake)
+

shared/cmake/libigl.cmake

@@ -491,3 +491,14 @@ install(EXPORT igl-export NAMESPACE igl::
 )
 export(TARGETS ${LIBIGL_ALL_MODULES} NAMESPACE igl:: FILE igl-export.cmake)
 
+# Write and install package configuration file
+configure_package_config_file(
+  ${CMAKE_CURRENT_LIST_DIR}/libigl-config.cmake.in
+  ${CMAKE_CURRENT_BINARY_DIR}/libigl-config.cmake
+  INSTALL_DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/igl/cmake
+)
+install(FILES
+  ${CMAKE_CURRENT_BINARY_DIR}/libigl-config.cmake
+  DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/igl/cmake
+)
+