mesa: add debug printer for primitive name

Add a simple version of _mesa_lookup_enum_by_nr() which expects a primitive
enum (GL_POINTS..GL_POLYGON).  This avoids some annoying duplicates
when looking up primitives, such as the GL_FALSE/GL_POINTS clash.

src/mesa/main/enums.c

@@ -5059,6 +5059,28 @@ const char *_mesa_lookup_enum_by_nr( int nr )
    }
 }
 
+/* Get the name of an enum given that it is a primitive type.  Avoids
+ * GL_FALSE/GL_POINTS ambiguity and others.
+ */
+const char *_mesa_lookup_prim_by_nr( int nr )
+{
+   switch (nr) {
+   case GL_POINTS: return "GL_POINTS";
+   case GL_LINES: return "GL_LINES";
+   case GL_LINE_STRIP: return "GL_LINE_STRIP";
+   case GL_LINE_LOOP: return "GL_LINE_LOOP";
+   case GL_TRIANGLES: return "GL_TRIANGLES";
+   case GL_TRIANGLE_STRIP: return "GL_TRIANGLE_STRIP";
+   case GL_TRIANGLE_FAN: return "GL_TRIANGLE_FAN";
+   case GL_QUADS: return "GL_QUADS";
+   case GL_QUAD_STRIP: return "GL_QUAD_STRIP";
+   case GL_POLYGON: return "GL_POLYGON";
+   case GL_POLYGON+1: return "OUTSIDE_BEGIN_END";
+   default: return "<invalid>";
+   }
+}
+
+
 int _mesa_lookup_enum_by_name( const char *symbol )
 {
    enum_elt * f = NULL;

src/mesa/main/enums.h

@@ -40,6 +40,12 @@
 #if defined(_HAVE_FULL_GL) && _HAVE_FULL_GL
 
 extern const char *_mesa_lookup_enum_by_nr( int nr );
+
+/* Get the name of an enum given that it is a primitive type.  Avoids
+ * GL_FALSE/GL_POINTS ambiguity and others.
+ */
+const char *_mesa_lookup_prim_by_nr( int nr );
+
 extern int _mesa_lookup_enum_by_name( const char *symbol );
 
 #else