Fixes error handling in LinkProgram

TRAC #11821
Signed-off-by: Nicolas Capens
Signed-off-by: Daniel Koch

Author:    Shannon Woods

git-svn-id: https://angleproject.googlecode.com/svn/trunk@136 736b8ea6-26fd-11df-bfd4-992fa37f6226

src/libGLESv2/libGLESv2.cpp

@@ -2950,7 +2950,14 @@ void __stdcall glLinkProgram(GLuint program)
 
             if (!programObject)
             {
-                return error(GL_INVALID_VALUE);
+                if (context->getShader(program))
+                {
+                    return error(GL_INVALID_OPERATION);
+                }
+                else
+                {
+                    return error(GL_INVALID_VALUE);
+                }
             }
 
             programObject->link();