waf: Implement module dependency checking in the build system

- Do not build a test if a dependency is not enabled.

- Perform a dependency check and generate an error if an enabled module
  depends on a disabled module.

Closes #4077

freebsd-to-rtems.py

@@ -150,6 +150,7 @@ try:
 
     build = builder.ModuleManager()
     libbsd.load(build)
+    build.loadConfig()
     build.generateBuild(only_enabled=False)
 
     dups = build.duplicateCheck()