[gegl] gegl-op.h: permit opting out of c-source meta-data

[Øyvind Kolås <ok src gnome org>]

commit 38e3d8232f4a862c8aa368b9ec8f12d780ae8b1c
Author: Øyvind Kolås <pippin gimp org>
Date:   Thu Mar 24 21:49:54 2016 +0100

    gegl-op.h: permit opting out of c-source meta-data

 gegl/gegl-op.h |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/gegl/gegl-op.h b/gegl/gegl-op.h
index 8d9db3a..7fc9988 100644
--- a/gegl/gegl-op.h
+++ b/gegl/gegl-op.h
@@ -29,8 +29,10 @@
 #define GEGL_HEADER(x) _GEGL_HEADER(x)
 
 #define GEGL_OP_C_FILE GEGL_HEADER(GEGL_OP_C_SOURCE)
+#ifndef GEGL_OP_NO_SOURCE
 #define GEGL_OP_C_FILE_SOURCE GEGL_HEADER(GEGL_OP_C_SOURCE.h)
 #endif
+#endif
 
 #ifndef GEGL_OP_C_FILE
 #ifdef GEGL_CHANT_C_FILE