[gegl] build: fix build when srcdir != builddir

[Jon Nordby <jonnor src gnome org>]

commit c81d18936d87d0406f3517fe4a7d0a85a264f96b
Author: Vadim Rutkovsky <vrutkovs redhat com>
Date:   Fri Jan 23 17:00:51 2015 +0100

    build: fix build when srcdir != builddir

 operations/Makefile-common.am |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/operations/Makefile-common.am b/operations/Makefile-common.am
index cf14ae0..7254b8c 100644
--- a/operations/Makefile-common.am
+++ b/operations/Makefile-common.am
@@ -32,5 +32,5 @@ AM_LDFLAGS = -avoid-version -export-dynamic -module $(no_undefined)
 
 ext_dir = $(libdir)/gegl- GEGL_API_VERSION@
 
-%.c.h: %.c $(top_builddir)/tools/csourcetostring.py
-       $(PYTHON) $(top_builddir)/tools/csourcetostring.py $<
+%.c.h: %.c $(top_srcdir)/tools/csourcetostring.py
+       $(PYTHON) $(top_srcdir)/tools/csourcetostring.py $<