cmake: add current directory to module search path in installed config file

Author: madebr

SDL2_mixerConfig.cmake.in

@@ -54,6 +54,8 @@ if(EXISTS "${CMAKE_CURRENT_LIST_DIR}/SDL2_mixer-shared-targets.cmake")
 endif()
 
 if(EXISTS "${CMAKE_CURRENT_LIST_DIR}/SDL2_mixer-static-targets.cmake")
+    set(_sdl_cmake_module_path "${CMAKE_MODULE_PATH}")
+    list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}")
 
     include(CMakeFindDependencyMacro)
     include(PkgConfigHelper)
@@ -106,6 +108,9 @@ if(EXISTS "${CMAKE_CURRENT_LIST_DIR}/SDL2_mixer-static-targets.cmake")
         find_dependency(wavpack)
     endif()
 
+    set(CMAKE_MODULE_PATH "${_sdl_cmake_module_path}")
+    unset(_sdl_cmake_module_path)
+
     if((NOT SDL2MIXER_VENDORED AND SDL2MIXER_MOD_MODPLUG) OR (HAIKU AND SDL2MIXER_MIDI_NATIVE))
         include(CheckLanguage)
         check_language(CXX)