gettext: Make ncurses dependency conditional on PACKAGECONFIG[msgcat-curses]

According to the documentation, the only reason for needing ncurses is
to support colour output from msgcat.  Make this optional so that
ncurses doesn't need to be built if colour output is not required.

(From OE-Core rev: a4040ad83984ee27fa9dc16d276c699d24b03b4e)

Signed-off-by: Phil Blundell <philb@gnu.org>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/gettext/gettext_0.18.2.bb

@@ -6,7 +6,7 @@ LICENSE = "GPLv3+ & LGPL-2.1+"
 LIC_FILES_CHKSUM = "file://COPYING;md5=d32239bcb673463ab874e80d47fae504"
 
 PR = "r0"
-DEPENDS = "gettext-native virtual/libiconv ncurses expat"
+DEPENDS = "gettext-native virtual/libiconv expat"
 DEPENDS_class-native = "gettext-minimal-native"
 PROVIDES = "virtual/libintl virtual/gettext"
 PROVIDES_class-native = "virtual/gettext-native"
@@ -15,6 +15,8 @@ SRC_URI = "${GNU_MIRROR}/gettext/gettext-${PV}.tar.gz \
 	   file://parallel.patch \
           "
 
+PACKAGECONFIG[msgcat-curses] = "--with-libncurses-prefix=${STAGING_LIBDIR}/..,--disable-curses,ncurses,"
+
 LDFLAGS_prepend_libc-uclibc = " -lrt -lpthread "
 
 SRC_URI[md5sum] = "0c86e5af70c195ab8bd651d17d783928"
@@ -30,7 +32,6 @@ EXTRA_OECONF += "--without-lispdir \
                  --disable-openmp \
                  --disable-acl \
                  --with-included-glib \
-                 --with-libncurses-prefix=${STAGING_LIBDIR}/.. \
                  --without-emacs \
                  --without-cvs \
                  --without-git \