The Mac Nvidia driver doesn't implement the result.clip part of
GL_NV_vertex_program2_option correctly. It complains about a syntax
error if "result.clip[0]" is used. "result.clip" compiles correctly, but
supports only one clipplane, and running the shader results in severe
rendering bugs.

The table is initialized on process attach, and should be freed on process
detach (which is where SECUR32_deinitSchannelSP gets called).

Two identical calls are made with the same parameters, and there are no
documented side effects of this function, so I removed one of them.

Using the ITextHost interface allows this notification to be received
for windowless richedit controls.  Windowed richedit conrols have an
ITextHost implementation that will fill in hwndFrom and idFrom, but
these should probably be initialized to 0 for windowless richedit
controls.