[babl] babl: initialize buffer pointers

[Øyvind "pippin" Kolås <ok src gnome org>]

commit ae5a6605cb16884173f0956d398dfdf53ddd77c5
Author: Øyvind Kolås <pippin gimp org>
Date:   Tue Jul 30 00:24:17 2019 +0200

    babl: initialize buffer pointers
    
    This silences a false warning from gcc, where it doesn't recognize the type
    of control flow occuring with the pre/post switches in the reference
    conversion.

 babl/babl-fish-reference.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/babl/babl-fish-reference.c b/babl/babl-fish-reference.c
index f9e2122..4c2e315 100644
--- a/babl/babl-fish-reference.c
+++ b/babl/babl-fish-reference.c
@@ -755,11 +755,11 @@ babl_fish_reference_process_double (const Babl *babl,
 
 
   void *source_double_buf_alloc = NULL;
-  void *source_double_buf;
+  void *source_double_buf       = NULL;
   void *rgba_double_buf_alloc   = NULL;
-  void *rgba_double_buf;
+  void *rgba_double_buf         = NULL;
   void *cmyka_double_buf_alloc  = NULL;
-  void *cmyka_double_buf;
+  void *cmyka_double_buf        = NULL;
   void *destination_double_buf_alloc = NULL;
   void *destination_double_buf;
   const void *type_double  = babl_type_from_id (BABL_DOUBLE);