[ftgrays] Fix typo in stand-alone mode (#54771).

* src/smooth/ftgrays.c (FT_THROW) [STANDALONE_ &&
FT_DEBUG_LEVEL_TRACE]: Fix call to `FT_ERR_CAT'.
diff --git a/ChangeLog b/ChangeLog
index c84c760..2894444 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2018-10-03  Werner Lemberg  <wl@gnu.org>
+
+	[ftgrays] Fix typo in stand-alone mode (#54771).
+
+	* src/smooth/ftgrays.c (FT_THROW) [STANDALONE_ &&
+	FT_DEBUG_LEVEL_TRACE]: Fix call to `FT_ERR_CAT'.
+
 2018-10-02  Werner Lemberg  <wl@gnu.org>
 
 	[psaux] Fix segfault.
diff --git a/src/smooth/ftgrays.c b/src/smooth/ftgrays.c
index e40a30d..871e981 100644
--- a/src/smooth/ftgrays.c
+++ b/src/smooth/ftgrays.c
@@ -222,10 +222,10 @@
 #endif
 
 #define FT_THROW( e )                               \
-          ( FT_Throw( FT_ERR_CAT( ErrRaster, e ),   \
+          ( FT_Throw( FT_ERR_CAT( ErrRaster_, e ),  \
                       __LINE__,                     \
                       __FILE__ )                  | \
-            FT_ERR_CAT( ErrRaster, e )            )
+            FT_ERR_CAT( ErrRaster_, e )           )
 
 #else /* !FT_DEBUG_LEVEL_TRACE */