[Python] Remove unused method function_exists(…) in capi.py

Author: practicalswift

tools/SourceKit/bindings/python/sourcekitd/capi.py

@@ -624,14 +624,6 @@ def get_sourcekitd_library(self):
 
         return library
 
-    def function_exists(self, name):
-        try:
-            getattr(self.lib, name)
-        except AttributeError:
-            return False
-
-        return True
-
 conf = Config()
 conf.lib.sourcekitd_initialize()