init StencilOpSeparate to NULL
diff --git a/src/mesa/drivers/common/driverfuncs.c b/src/mesa/drivers/common/driverfuncs.c
index 93d195d..db4ff2a 100644
--- a/src/mesa/drivers/common/driverfuncs.c
+++ b/src/mesa/drivers/common/driverfuncs.c
@@ -165,6 +165,7 @@
    driver->StencilFunc = NULL;
    driver->StencilMask = NULL;
    driver->StencilOp = NULL;
+   driver->StencilOpSeparate = NULL;
    driver->ActiveStencilFace = NULL;
    driver->TexGen = NULL;
    driver->TexEnv = NULL;