[gimp] app: also search interpreters executable in $PATH.

[Jehan <jehanp src gnome org>]

commit 0af3ae81ff43d5a7cc94c7bf54afa943721a07a9
Author: Jehan <jehan girinstud io>
Date:   Sat Jun 16 03:14:43 2018 +0200

    app: also search interpreters executable in $PATH.
    
    Same as we did for binfmt-style lines, if the executable part (for
    instance in `pygimp.interp`) is not an absolute path, let's allow
    ourselves to find it in the environment $PATH.
    
    (cherry picked from commit f3c5ed55c884dacac96b0aae5d3af65f7ef7a73f)

 app/plug-in/gimpinterpreterdb.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)
---
diff --git a/app/plug-in/gimpinterpreterdb.c b/app/plug-in/gimpinterpreterdb.c
index 5597e54959..4f981237d3 100644
--- a/app/plug-in/gimpinterpreterdb.c
+++ b/app/plug-in/gimpinterpreterdb.c
@@ -294,14 +294,22 @@ gimp_interpreter_db_add_program (GimpInterpreterDB  *db,
 
   if (! g_file_test (program, G_FILE_TEST_IS_EXECUTABLE))
     {
-      g_message (_("Bad interpreter referenced in interpreter file %s: %s"),
-                 gimp_file_get_utf8_name (file),
-                 gimp_filename_to_utf8 (program));
-      return;
+      program = g_find_program_in_path (program);
+      if (! program || ! g_file_test (program, G_FILE_TEST_IS_EXECUTABLE))
+        {
+          g_message (_("Bad interpreter referenced in interpreter file %s: %s"),
+                     gimp_file_get_utf8_name (file),
+                     gimp_filename_to_utf8 (program));
+          if (program)
+            g_free (program);
+          return;
+        }
     }
+  else
+    program = g_strdup (program);
 
   if (! g_hash_table_lookup (db->programs, name))
-    g_hash_table_insert (db->programs, g_strdup (name), g_strdup (program));
+    g_hash_table_insert (db->programs, g_strdup (name), program);
 }
 
 static void