[grilo-plugins] lua-factory: Fix compile-time warning with GCC7

[Bastien Nocera <hadess src gnome org>]

commit 891bd77d569d2b7e7c9d7a9b2c049228ed01684f
Author: Bastien Nocera <hadess hadess net>
Date:   Thu Jun 29 17:27:02 2017 +0200

    lua-factory: Fix compile-time warning with GCC7
    
    duplicate ‘const’ declaration specifier [-Wduplicate-decl-specifier]
    
    The warning was added in:
    https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43651
    just for this purpose.
    
    "
    int foo(const char const *data);
    ^~~~~~
    1 warning generated.
    
    [...] In that case it was clearly a mistake, because the author meant
    'const char *const data' [...]
    "

 src/lua-factory/grl-lua-factory.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/lua-factory/grl-lua-factory.c b/src/lua-factory/grl-lua-factory.c
index f069d12..850c7bc 100644
--- a/src/lua-factory/grl-lua-factory.c
+++ b/src/lua-factory/grl-lua-factory.c
@@ -919,7 +919,7 @@ keys_table_array_to_list (lua_State *L,
 static gboolean
 validate_account_feature (const char *lua_account_feature)
 {
-  const char const *features[] = {
+  const char * const features[] = {
     "photos",
     "read-later",
     "music",