Add package libglvnd (#49214)

* Add package libglvnd
  Signed-off-by: Shane Nehring <snehring@iastate.edu>
* libglvnd: add virtual defaults
  Signed-off-by: Shane Nehring <snehring@iastate.edu>

---------

Signed-off-by: Shane Nehring <snehring@iastate.edu>

etc/spack/defaults/packages.yaml

@@ -24,13 +24,14 @@ packages:
       cxx: [gcc]
       D: [ldc]
       daal: [intel-oneapi-daal]
+      egl: [libglvnd]
       elf: [elfutils]
       fftw-api: [fftw, amdfftw]
       flame: [libflame, amdlibflame]
       fortran: [gcc]
       fortran-rt: [gcc-runtime, intel-oneapi-runtime]
       fuse: [libfuse]
-      gl: [glx, osmesa]
+      gl: [glx, osmesa, libglvnd]
       glu: [mesa-glu, openglu]
       golang: [go, gcc]
       go-or-gccgo-bootstrap: [go-bootstrap, gcc]

var/spack/repos/builtin/packages/libglvnd/package.py

@@ -0,0 +1,34 @@
+# Copyright Spack Project Developers. See COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from spack.package import *
+
+
+class Libglvnd(MesonPackage):
+    """libglvnd is a vendor-neutral dispatch layer for arbitrating OpenGL API calls
+    between multiple vendors."""
+
+    homepage = "https://gitlab.freedesktop.org/glvnd/libglvnd"
+    url = "https://gitlab.freedesktop.org/glvnd/libglvnd/-/archive/v1.7.0/libglvnd-v1.7.0.tar.gz"
+
+    maintainers("snehring")
+
+    license(
+        """MIT-feh AND MIT-Modern-Variant AND BSD-1-Clause AND BSD-3-Clause
+           AND GPL-3.0-or-later WITH Autoconf-exception-macro""",
+        checked_by="snehring",
+    )
+
+    version("1.7.0", sha256="2b6e15b06aafb4c0b6e2348124808cbd9b291c647299eaaba2e3202f51ff2f3d")
+    version("1.6.0", sha256="efc756ffd24b24059e1c53677a9d57b4b237b00a01c54a6f1611e1e51661d70c")
+
+    depends_on("c", type="build")
+    depends_on("cxx", type="build")
+
+    depends_on("libxext")
+    depends_on("libx11")
+    depends_on("xorgproto")
+
+    provides("egl")
+    provides("gl")