libvips: use the new gettext logic

This commit switches to use the new gettext logic, which involves:

 - using TARGET_NLS_DEPENDENCIES instead of hand-encoded dependencies
   on gettext/host-gettext

 - dropping BR2_PACKAGE_GETTEXT selection. We adjust the comment
   explaining the BR2_USE_WCHAR dependency, since gettext is no longer
   the reason for this dependency.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/libvips/Config.in

@@ -1,6 +1,6 @@
 config BR2_PACKAGE_LIBVIPS
 	bool "libvips"
-	depends on BR2_USE_WCHAR # gettext, libglib2
+	depends on BR2_USE_WCHAR # libglib2
 	depends on BR2_TOOLCHAIN_HAS_THREADS # libglib2
 	depends on BR2_USE_MMU # fork()
 	# C++ support is required to build libvips
@@ -8,7 +8,6 @@ config BR2_PACKAGE_LIBVIPS
 	depends on BR2_INSTALL_LIBSTDCPP
 	select BR2_PACKAGE_LIBGLIB2
 	select BR2_PACKAGE_LIBXML2
-	select BR2_PACKAGE_GETTEXT if BR2_NEEDS_GETTEXT_IF_LOCALE
 	help
 	  libvips is a 2D image processing library. Compared to
 	  similar libraries, libvips runs quickly and uses little

package/libvips/libvips.mk

@@ -41,7 +41,7 @@ LIBVIPS_CONF_OPTS = \
 LIBVIPS_INSTALL_STAGING = YES
 LIBVIPS_DEPENDENCIES = \
 	host-pkgconf libglib2 \
-	libxml2 $(if $(BR2_NEEDS_GETTEXT_IF_LOCALE),gettext)
+	libxml2 $(TARGET_NLS_DEPENDENCIES)
 
 # --disable-cxx is broken upstream
 # https://github.com/jcupitt/libvips/issues/231