Fix dynamic library handling for LibUSB

`target_get_dynamic_library` should not be called if `SDL_HIDAPI_LIBUSB_SHARED` is set to OFF, it otherwise causes a warning at best, or a build failure if libusb is provided by a parent project and not installed on the system

cmake/sdlchecks.cmake

@@ -1270,12 +1270,15 @@ macro(CheckHIDAPI)
         cmake_pop_check_state()
         if(HAVE_LIBUSB_H)
           set(HAVE_LIBUSB TRUE)
-          target_get_dynamic_library(dynamic_libusb LibUSB::LibUSB)
-          if(SDL_HIDAPI_LIBUSB_SHARED AND dynamic_libusb)
-            set(HAVE_HIDAPI_LIBUSB_SHARED ON)
-            set(SDL_LIBUSB_DYNAMIC "\"${dynamic_libusb}\"")
-            sdl_link_dependency(hidapi INCLUDES $<TARGET_PROPERTY:LibUSB::LibUSB,INTERFACE_INCLUDE_DIRECTORIES>)
-          else()
+          if(SDL_HIDAPI_LIBUSB_SHARED)
+            target_get_dynamic_library(dynamic_libusb LibUSB::LibUSB)
+            if(dynamic_libusb)
+              set(HAVE_HIDAPI_LIBUSB_SHARED ON)
+              set(SDL_LIBUSB_DYNAMIC "\"${dynamic_libusb}\"")
+              sdl_link_dependency(hidapi INCLUDES $<TARGET_PROPERTY:LibUSB::LibUSB,INTERFACE_INCLUDE_DIRECTORIES>)
+            endif()
+          endif()
+          if(NOT HAVE_HIDAPI_LIBUSB_SHARED)
             sdl_link_dependency(hidapi LIBS LibUSB::LibUSB PKG_CONFIG_SPECS "${LibUSB_PKG_CONFIG_SPEC}" CMAKE_MODULE LibUSB)
           endif()
         endif()