svga: avoid freeing non-malloced memory

svga: avoid freeing non-malloced memory

svga_shader_expand() will fall back to using non-malloced memory for
emit.buf if malloc fails. We should check if the memory is malloced
before freeing it in the error path of svga_tgsi_vgpu9_translate.

Original patch by Thomas Hindoe Paaboel Andersen <phomes@gmail.com>.
Remove trivial svga_destroy_shader_emitter() function, by BrianP.

Signed-off-by: Brian Paul <brianp@vmware.com>