[gimp] plug-ins: use only "#?" for RGBE magic number.

[Jehan Pagès <jehanp src gnome org>]

commit 3cca5a0a7bd34166b27461db7f1482b6d6420fe7
Author: Jehan <jehan girinstud io>
Date:   Sat Jan 13 00:39:17 2018 +0100

    plug-ins: use only "#?" for RGBE magic number.
    
    It seems that various software use something different after the "#?",
    and even Blender code just ended up only use these 2 characters as magic
    number. See also bug 792453.

 plug-ins/common/file-gegl.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/plug-ins/common/file-gegl.c b/plug-ins/common/file-gegl.c
index a039973..fe1e964 100644
--- a/plug-ins/common/file-gegl.c
+++ b/plug-ins/common/file-gegl.c
@@ -73,7 +73,7 @@ static const FileFormat file_formats[] =
     N_("Radiance RGBE"),
     "image/vnd.radiance",
     "hdr",
-    "0,string,?#RADIANCE\x0a",
+    "0,string,?#",
 
     "file-gegl-load-rgbe",
     "Load files in the RGBE file format",