libvisual/gettext.h: Address redefinition of macro gettext_noop

Symptom was:
> ./gettext.h:71: error: "gettext_noop" redefined [-Werror]
>    71 | #define gettext_noop(String) String
>       |
> ./gettext.h:49: note: this is the location of the previous definition
>    49 | # define gettext_noop(Msgid) ((const char *) (Msgid))
>       |

Author: hartwork

libvisual/libvisual/gettext.h

@@ -46,7 +46,6 @@
    On pre-ANSI systems without 'const', the config.h file is supposed to
    contain "#define const".  */
 # define gettext(Msgid) ((const char *) (Msgid))
-# define gettext_noop(Msgid) ((const char *) (Msgid))
 # define dgettext(Domainname, Msgid) ((const char *) (Msgid))
 # define dcgettext(Domainname, Msgid, Category) ((const char *) (Msgid))
 # define ngettext(Msgid1, Msgid2, N) \
@@ -68,6 +67,7 @@
    and other string expressions won't work.
    The macro's expansion is not parenthesized, so that it is suitable as
    initializer for static 'char[]' or 'const char[]' variables.  */
+#undef gettext_noop
 #define gettext_noop(String) String
 
 #define N_(String) gettext_noop(String)