[gexiv2] Fix gtk-doc warning when building on Windows

[Jens Georg <jensgeorg src gnome org>]

commit fef8429c80b1d8abd9f238dc49d5bdc8ff1eba3b
Author: postscript-dev <43813-postscript-dev users noreply gitlab gnome org>
Date:   Fri Feb 26 13:26:36 2021 +0000

    Fix gtk-doc warning when building on Windows
    
    Commit 638eb5ec added `override` and removed `virtual` to `StreamIo` class,
    causing a warning when building the docs on Windows (MinGW/MSYS2). As the
    class is not included in the documentation, the solution is to exclude the
    file from the gtk-doc build.
    
    The issue is discussed in Commit 638eb5ec.
    
    The issue is raised upstream [here](GNOME/gtk-doc#140).

 docs/reference/meson.build | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/docs/reference/meson.build b/docs/reference/meson.build
index 457a2e3..5ba90cd 100644
--- a/docs/reference/meson.build
+++ b/docs/reference/meson.build
@@ -3,5 +3,6 @@ gnome.gtkdoc('gexiv2',
              main_xml : 'gexiv2-docs.xml',
              gobject_typesfile : 'gexiv2.types',
              src_dir : ['gexiv2'],
+             ignore_headers: ['gexiv2-stream-io.h'],
              dependencies : libgexiv2,
              install : true)