Fix shared lib name on macOS

When on macOS, reverse the shared lib naming convention (as compared to
Linux) to put the version number before the the lib extension.

Fixes #2760

assimpTargets-release.cmake.in

@@ -63,7 +63,11 @@ if(MSVC)
 else()
   set(ASSIMP_LIBRARY_SUFFIX "@ASSIMP_LIBRARY_SUFFIX@" CACHE STRING "the suffix for the assimp libraries" )
   if(ASSIMP_BUILD_SHARED_LIBS)
-    set(sharedLibraryName "libassimp${ASSIMP_LIBRARY_SUFFIX}@CMAKE_SHARED_LIBRARY_SUFFIX@.@ASSIMP_VERSION_MAJOR@")
+    if(APPLE)
+      set(sharedLibraryName "libassimp${ASSIMP_LIBRARY_SUFFIX}.@ASSIMP_VERSION_MAJOR@@CMAKE_SHARED_LIBRARY_SUFFIX@")
+    else()
+      set(sharedLibraryName "libassimp${ASSIMP_LIBRARY_SUFFIX}@CMAKE_SHARED_LIBRARY_SUFFIX@.@ASSIMP_VERSION_MAJOR@")
+    endif()
     set_target_properties(assimp::assimp PROPERTIES
       IMPORTED_SONAME_RELEASE "${sharedLibraryName}"
       IMPORTED_LOCATION_RELEASE "${_IMPORT_PREFIX}/lib/${sharedLibraryName}"