GL_EXT_paletted_texture functions should alias GL_SGI_color_table functions.

GL_EXT_paletted_texture functions should alias GL_SGI_color_table functions.

The functions for GL_EXT_paletted_texture that do not share GLX
protocol with GL_ARB_imaging are supposed to alias the similar
functions from GL_SGI_color_table.  They didn't.  This patch corrects
this problem and enables GLX protocol for both extensions.

Since this removes 3 entries from the dispatch table, this change
creates a lot of changes in the generated files.