[gimp] plug-ins: .jpc is another known extension for JPEG 2000 codestream.

[Jehan Pagès <jehanp src gnome org>]

commit 5e5fa4a024941219a46eee51052fe9e7739572f6
Author: Jehan <jehan girinstud io>
Date:   Tue Mar 20 02:05:49 2018 +0100

    plug-ins: .jpc is another known extension for JPEG 2000 codestream.
    
    Even though I haven't seen working samples with this extension,
    according to some references, this is a common extension for compressed
    JPEG 2000 code stream. Also our old plug-in was listing this extension,
    so let's do so now as well.
    
    To this day, the only 2 extensions we used to list in the JasPer-based
    plug-in and not in the OpenJPEG one are .jpf and .jpx (JPEG 2000 Part-2)
    since OpenJPEG does not have support yet. But actually I think the old
    plug-in may have simply been "lying" since JasPer website says the
    library is meant to implement JPEG-2000 Part-1 standard.
    So I believe we are now on par (and even better on many aspects) with
    the former plug-in implementation based on libjasper.

 plug-ins/common/file-jp2-load.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/plug-ins/common/file-jp2-load.c b/plug-ins/common/file-jp2-load.c
index a5123ee..ecf689a 100644
--- a/plug-ins/common/file-jp2-load.c
+++ b/plug-ins/common/file-jp2-load.c
@@ -168,7 +168,7 @@ query (void)
                           G_N_ELEMENTS (load_return_vals),
                           load_args, load_return_vals);
   gimp_register_magic_load_handler (LOAD_J2K_PROC,
-                                    "j2k,j2c",
+                                    "j2k,j2c,jpc",
                                     "",
                                     "0,string,\xff\x4f\xff\x51\x00");
   gimp_register_file_handler_mime (LOAD_J2K_PROC, "image/x-jp2-codestream");