codingstyle: make PortageInternals an error instead of a warning

Author: radhermit

src/pkgcheck/checks/codingstyle.py

@@ -97,7 +97,7 @@ def __init__(self, command, line, lineno, **kwargs):
         self.lineno = lineno
 
 
-class PortageInternals(_CommandResult, base.Warning):
+class PortageInternals(_CommandResult, base.Error):
     """Ebuild uses a function or variable internal to portage."""
 
     @property