remove RuntimeError from buildnml

cime_config/buildnml

@@ -78,11 +78,11 @@ def buildnml(case, caseroot, compname):
             buildcpp = import_from_file("buildcpp", cmd)
             _ = buildcpp.buildcpp(case)
         except:
-            raise RuntimeError("CAM's 'buildcpp' script failed to run properly.")
+            logger.warning("     ...cam buildcpp exited with error")
 
     # Verify that we have a config_cache file (generated by the call to buildcpp)
     expect(os.path.isfile(filename),
-           " Missing config_cache.xml - cannot run build-namelist")
+           " Missing CAM's config_cache.xml - cannot run build-namelist")
 
     #--------------------------------------------------------------------
     # Invoke cam build-namelist - output will go in $CASEROOT/Buildconf/camconf