Add errorlevel checking after each custom command in a sequence.

This makes the behavior of the build with the Visual Studio generators
equivalent to the behavior of makefile based builds. After an error
in a custom command sequence, the build stops and reports an error
rather than executing the remaining commands in the sequence.

Source/cmLocalVisualStudioGenerator.cxx

@@ -230,7 +230,15 @@ cmLocalVisualStudioGenerator
                                        escapeAllowMakeVars);
         }
       }
-    }
-  return script;
+
+    // After each custom command, check for an error result.
+    // If there was an error, jump to the VCReportError label,
+    // skipping the run of any subsequent commands in this
+    // sequence.
+    //
+    script += newline_text;
+    script += "if errorlevel 1 goto VCReportError";
     }
 
+  return script;
+}