sensorgraph: add missing glDeleteShader calls

sensor-graph/app/src/main/jni/sensorgraph.cpp

@@ -144,6 +144,8 @@ class sensorgraph {
         GLint programLinked = 0;
         glGetProgramiv(program, GL_LINK_STATUS, &programLinked);
         assert(programLinked != 0);
+        glDeleteShader(vertexShader);
+        glDeleteShader(pixelShader);
         return program;
     }