bitbake: data_smart: Add hasOverrides method to public datastore API

There are some cases where the metadata needs to check if a variable
has any overrides set, even if they are currently inactive. That code
currently pokes into datastore internals. Add API instead to replace
and avoid that.

(Bitbake rev: c885e5542dcf760b8fc5881e385abb4a10020874)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/data_smart.py

@@ -488,6 +488,8 @@ class DataSmart(MutableMapping):
         else:
             self.initVar(var)
 
+    def hasOverrides(self, var):
+        return var in self.overridedata
 
     def setVar(self, var, value, **loginfo):
         #print("var=" + str(var) + "  val=" + str(value))