Need to store vendor and renderer strings in the context.

As it was, we always returned the same pointer.  So glxinfo, which calls
glGetString() before printing anything, was printing the same string for
both vendor and renderer.

src/mesa/state_tracker/st_cb_strings.c

@@ -46,8 +46,6 @@ st_get_string(GLcontext * ctx, GLenum name)
 {
    struct st_context *st = st_context(ctx);
    struct pipe_context *pipe = st->pipe;
-   static char buffer[128];
-
 
    switch (name) {
    case GL_VENDOR: {
@@ -59,20 +57,20 @@ st_get_string(GLcontext * ctx, GLenum name)
        * additional string allows "and XyzCorp" to reflect this.
        */
       if (vendor && strcmp(vendor, tungsten) != 0)
-	 snprintf(buffer, sizeof(buffer), "%s and %s",	tungsten, vendor);
+	 snprintf(st->vendor, sizeof(st->vendor),
+                  "%s and %s", tungsten, vendor);
       else
-	 snprintf(buffer, sizeof(buffer), "%s",	tungsten);
+	 snprintf(st->vendor, sizeof(st->vendor), "%s", tungsten);
 
-      return (GLubyte *) buffer;
-      break;
+      return (GLubyte *) st->vendor;
    }
 
    case GL_RENDERER:
-      snprintf(buffer, sizeof(buffer), "TG3D, %s on %s", 
+      snprintf(st->renderer, sizeof(st->renderer), "TG3D, %s on %s", 
 	       pipe->get_name( pipe ),
 	       pipe->winsys->get_name( pipe->winsys ));
 
-      return (GLubyte *) buffer;
+      return (GLubyte *) st->renderer;
 
    default:
       return NULL;

src/mesa/state_tracker/st_context.h

@@ -97,6 +97,9 @@ struct st_context
       GLuint frontbuffer_dirty:1;
    } flags;
 
+   char vendor[100];
+   char renderer[100];
+
    /* State to be validated:
     */
    struct st_tracked_state **atoms;