usermods/*/setup_deps.py: Check lib_deps for deps

Check the safest possible location for final information on what
components are actually being linked in.  This demonstrates a safe
approach that works even for out-of-tree modules.

usermods/PWM_fan/setup_deps.py

@@ -1,11 +1,12 @@
+from platformio.package.meta import PackageSpec
 Import('env')
 
 
-usermods = env.GetProjectOption("custom_usermods","").split()
+libs = [PackageSpec(lib).name for lib in env.GetProjectOption("lib_deps",[])]
 # Check for dependencies
-if "Temperature" in usermods:
+if "Temperature" in libs:
     env.Append(CPPDEFINES=[("USERMOD_DALLASTEMPERATURE")])
-elif "sht" in usermods:
+elif "sht" in libs:
     env.Append(CPPDEFINES=[("USERMOD_SHT")])
-elif "PWM_fan" in usermods:  # The script can be run if this module was previously selected
+elif "PWM_fan" in libs:  # The script can be run if this module was previously selected
     raise RuntimeError("PWM_fan usermod requires Temperature or sht to be enabled")