gcal: add dependency on gettext/libintl
gcal: add dependency on gettext/libintl

* If not using it, gcal will always show dates in english.
* Also link it as "cal" so it can replace the built-in one.

haikuports/haikuports,koletzky/haikuports,haikuports/haikuports,koletzky/haikuports,moochris/haikuports,moochris/haikuports,haikuports/haikuports,moochris/haikuports,haikuports/haikuports,Begasus/haikuports,miqlas/haikuports,Begasus/haikuports,koletzky/haikuports,haikuports/haikuports,Begasus/haikuports,Begasus/haikuports,nielx/haikuports,miqlas/haikuports,nielx/haikuports,miqlas/haikuports,nielx/haikuports,Begasus/haikuports