gnu: Add libadwaita.

* gnu/packages/gnome.scm (libadwaita): New variable.

gnu/packages/gnome.scm

@@ -12495,3 +12495,46 @@ (define-public ocrfeeder
     (description "OCRFeeder is a complete Optical Character Recognition and
 Document Analysis and Recognition program.")
     (license license:gpl3+)))
+
+(define-public libadwaita
+  (let ((commit "8d66b987a19979d9d7b85dacc6bad5ce0c8743fe")
+        (revision "1"))
+    (package
+      (name "libadwaita")
+      (version (git-version "0.0.1" revision commit))
+      (source (origin
+                (method git-fetch)
+                (uri (git-reference
+                      (url "https://gitlab.gnome.org/GNOME/libadwaita.git")
+                      (commit commit)))
+                (file-name (git-file-name name version))
+                (sha256
+                 (base32
+                  "0i3wav6jsyi4w4i2r1rad769m5y5s9djj4zqb7dfyh0bad24ba3q"))))
+      (build-system meson-build-system)
+      (arguments
+       `(#:phases
+         (modify-phases %standard-phases
+           (add-before 'check 'pre-check
+             (lambda* (#:key inputs #:allow-other-keys)
+               ;; Tests require a running X server.
+               (system "Xvfb :1 &")
+               (setenv "DISPLAY" ":1"))))))
+      (native-inputs
+       `(("sassc" ,sassc)
+         ("glib:bin" ,glib "bin")
+         ("gtk-doc" ,gtk-doc/stable)
+         ("pkg-config" ,pkg-config)
+         ("vala" ,vala)
+         ("xvfb" ,xorg-server-for-tests)))
+      (inputs
+       `(("gtk" ,gtk)
+         ("gobject-introspection" ,gobject-introspection)
+         ("libportal" ,libportal)))
+      (home-page "https://gnome.pages.gitlab.gnome.org/libadwaita/")
+      (synopsis "Building blocks for GNOME applications")
+      (description
+       "@code(libadwaita) offers widgets and objects to build GNOME
+applications scaling from desktop workstations to mobile phones.  It is the
+successor of @code{libhandy} for GTK4.")
+      (license license:lgpl2.1+))))