cmake: Only install fmt headers when SPDLOG_FMT_EXTERNAL is not defined.

CMakeLists.txt

@@ -184,9 +184,14 @@ if (SPDLOG_INSTALL)
     #---------------------------------------------------------------------------------------
     # Include files
     #---------------------------------------------------------------------------------------
-    install(DIRECTORY include/ DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}")
+    install(DIRECTORY include/ DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}" PATTERN "fmt/bundled" EXCLUDE)
     install(TARGETS spdlog spdlog_header_only EXPORT spdlog DESTINATION "${CMAKE_INSTALL_LIBDIR}/spdlog")
 
+    if(NOT SPDLOG_FMT_EXTERNAL)
+        install(DIRECTORY include/${PROJECT_NAME}/fmt/bundled/
+                DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/${PROJECT_NAME}/fmt/bundled/")
+    endif()
+
     #---------------------------------------------------------------------------------------
     # Package and version files
     #---------------------------------------------------------------------------------------