gltrace: Make sure device is debuggable.

void initEglDebugLevel() {

    int propertyLevel = 0;

    char value[PROPERTY_VALUE_MAX];

    // check system property only on userdebug or eng builds

    property_get("ro.debuggable", value, "0");

    if (value[0] == '0')

        return;

    property_get("debug.egl.debug_proc", value, "");

    if (strlen(value) > 0) {

        long pid = getpid();