meson: convert po/

Meson warns if xgettext is not found.  In the future we may want to add
a required argument to i18n.gettext(); in the meanwhile, I am adding a
--enable-gettext/--disable-gettext option and feature detection in
configure.  This preserves QEMU's default behavior of detecting system
features, without any warning, if neither --enable-* nor --disable-*
is requested.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

configure

@@ -569,6 +569,7 @@ secret_keyring=""
 libdaxctl=""
 meson=""
 skip_meson=no
+gettext=""
 
 bogus_os="no"
 malloc_trim=""
@@ -1161,6 +1162,10 @@ for opt do
   ;;
   --enable-vnc) vnc="enabled"
   ;;
+  --disable-gettext) gettext="false"
+  ;;
+  --enable-gettext) gettext="true"
+  ;;
   --oss-lib=*) oss_lib="$optarg"
   ;;
   --audio-drv-list=*) audio_drv_list="$optarg"
@@ -3032,6 +3037,19 @@ if test "$whpx" != "no" ; then
     fi
 fi
 
+##########################################
+# gettext probe
+if test "$gettext" != "false" ; then
+  if has xgettext; then
+    gettext=true
+  else
+    if test "$gettext" = "true" ; then
+      feature_not_found "gettext" "Install xgettext binary"
+    fi
+    gettext=false
+  fi
+fi
+
 ##########################################
 # Sparse probe
 if test "$sparse" != "no" ; then
@@ -8099,7 +8117,7 @@ DIRS="$DIRS docs docs/interop fsdev scsi"
 DIRS="$DIRS pc-bios/optionrom pc-bios/s390-ccw"
 DIRS="$DIRS roms/seabios"
 LINKS="Makefile"
-LINKS="$LINKS tests/tcg/lm32/Makefile po/Makefile"
+LINKS="$LINKS tests/tcg/lm32/Makefile"
 LINKS="$LINKS tests/tcg/Makefile.target"
 LINKS="$LINKS pc-bios/optionrom/Makefile pc-bios/keymaps"
 LINKS="$LINKS pc-bios/s390-ccw/Makefile"
@@ -8231,6 +8249,7 @@ NINJA=$PWD/ninjatool $meson setup \
         -Db_coverage=$(if test "$gcov" = yes; then echo true; else echo false; fi) \
 	-Dsdl=$sdl -Dsdl_image=$sdl_image \
 	-Dvnc=$vnc -Dvnc_sasl=$vnc_sasl -Dvnc_jpeg=$vnc_jpeg -Dvnc_png=$vnc_png \
+	-Dgettext=$gettext \
         $cross_arg \
         "$PWD" "$source_path"