message: Fix reading back index buffer to determine client vertex range.
diff: @@ -774,8 +774,8 @@ WrappedOpenGL::ClientMemoryData *WrappedOpenGL::CopyClientMemoryArrays(GLint fir
  if(idxbuf != 0)
  {
  // If we were using a real index buffer, read it back to check its range.
  - mmIndices = m_Real.glMapBufferRange(eGL_ELEMENT_ARRAY_BUFFER, (size_t)indices,
  - idxlen - (size_t)indices, eGL_MAP_READ_BIT);
  + mmIndices = m_Real.glMapBufferRange(eGL_ELEMENT_ARRAY_BUFFER, (size_t)indices, idxlen,
  + eGL_MAP_READ_BIT);
  }
  size_t min = ~0u, max = 0;
  