Fix the targets variable in pc files

This is meant as a space-separated list of
string, so escaping the spaces is uncalled
for.

Fixes: #4486

meson.build

@@ -861,7 +861,7 @@ common_pc_variables = [
 foreach pkg: pkgs
   pkg_config.generate(
     filebase: pkg,
-    variables: common_pc_variables,
+    unescaped_variables: common_pc_variables,
     name: 'GTK',
     description: 'GTK Graphical UI Library',
     requires: gdk_packages + gsk_packages + gtk_packages,
@@ -877,7 +877,7 @@ endforeach
 if os_unix
   pkg_config.generate(
     filebase: 'gtk4-unix-print',
-    variables: common_pc_variables,
+    unescaped_variables: common_pc_variables,
     name: 'GTK',
     description: 'GTK Unix print support',
     requires: ['gtk4'] + gtk_packages,