tgsi: add tgsi_shader_info::writes_clipvertex

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

src/gallium/auxiliary/tgsi/tgsi_scan.c

@@ -245,6 +245,9 @@ tgsi_scan_shader(const struct tgsi_token *tokens,
                      else if (semName == TGSI_SEMANTIC_PSIZE) {
                         info->writes_psize = TRUE;
                      }
+                     else if (semName == TGSI_SEMANTIC_CLIPVERTEX) {
+                        info->writes_clipvertex = TRUE;
+                     }
                   }
 
                   if (procType == TGSI_PROCESSOR_FRAGMENT) {

src/gallium/auxiliary/tgsi/tgsi_scan.h

@@ -77,6 +77,7 @@ struct tgsi_shader_info
    boolean uses_primid;
    boolean uses_frontface;
    boolean writes_psize;
+   boolean writes_clipvertex;
    boolean writes_viewport_index;
    boolean writes_layer;
    boolean is_msaa_sampler[PIPE_MAX_SAMPLERS];