wined3d: Add support for ARB_shadow.

dlls/wined3d/directx.c

@@ -74,6 +74,7 @@ static const struct {
     {"GL_ARB_shader_objects",               ARB_SHADER_OBJECTS,             0                           },
     {"GL_ARB_shader_texture_lod",           ARB_SHADER_TEXTURE_LOD,         0                           },
     {"GL_ARB_shading_language_100",         ARB_SHADING_LANGUAGE_100,       0                           },
+    {"GL_ARB_shadow",                       ARB_SHADOW,                     0                           },
     {"GL_ARB_sync",                         ARB_SYNC,                       0                           },
     {"GL_ARB_texture_border_clamp",         ARB_TEXTURE_BORDER_CLAMP,       0                           },
     {"GL_ARB_texture_compression",          ARB_TEXTURE_COMPRESSION,        0                           },

dlls/wined3d/wined3d_gl.h

@@ -1754,6 +1754,7 @@ typedef enum wined3d_gl_extension
     ARB_SHADER_OBJECTS,
     ARB_SHADER_TEXTURE_LOD,
     ARB_SHADING_LANGUAGE_100,
+    ARB_SHADOW,
     ARB_SYNC,
     ARB_TEXTURE_BORDER_CLAMP,
     ARB_TEXTURE_COMPRESSION,
@@ -2404,6 +2405,14 @@ typedef unsigned int GLhandleARB;
 #define GL_SHADING_LANGUAGE_VERSION_ARB                     0x8b8c
 #endif
 
+/* GL_ARB_shadow */
+#ifndef GL_ARB_shadow
+#define GL_ARB_shadow 1
+#define GL_TEXTURE_COMPARE_MODE_ARB                         0x884c
+#define GL_TEXTURE_COMPARE_FUNC_ARB                         0x884d
+#define GL_COMPARE_R_TO_TEXTURE_ARB                         0x884e
+#endif
+
 /* GL_ARB_sync */
 #ifndef GL_ARB_sync
 #define GL_ARB_sync 1