Install gversionmacros.h in the right place

The gversionmacros.h header is referenced from glib/, so it needs to go
into glib's include directory, not in the top-level alongside glib.h,
glib-object.h, gmodule.h, and glib-unix.h.

glib/meson.build

diff --git a/glib/meson.build b/glib/meson.build
index 85f9e18..ac0911d 100644
--- a/glib/meson.build
+++ b/glib/meson.build
@@ -12,8 +12,8 @@
   output: 'gversionmacros.h',
   command: [gen_visibility_macros, meson.project_version(), 'versions-macros', '@INPUT@', '@OUTPUT@'],
   install: true,
-  install_dir: glib_includedir,
-  install_tag : 'devel',
+  install_dir: glib_sub_includedir,
+  install_tag: 'devel',
 )
 
 gvisibility_h = custom_target(
@@ -21,6 +21,7 @@
   command: [gen_visibility_macros, meson.project_version(), 'visibility-macros', 'GLIB', '@OUTPUT@'],
   install: true,
   install_dir: glib_sub_includedir,
+  install_tag: 'devel',
 )
 
 glib_built_headers = [gversionmacros_h, gvisibility_h]