new package: libglvnd (#12183)

* new package: libglvnd

* remove virtual provides from libglvnd

libglvnd does not provide them directly, but
through implementations that depend on it.

* fix flake8 errors

* libglvnd: fix style/remove unecessary variants

* remove older libglvnd version

* explicitly enable all libglvnd stubs

* libglvnd: conflict with non-linux platform

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

@@ -0,0 +1,45 @@
+# Copyright 2013-2019 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from spack import *
+
+
+class Libglvnd(AutotoolsPackage):
+    """The GL Vendor-Neutral Dispatch library
+
+    libglvnd is a vendor-neutral dispatch layer for arbitrating OpenGL API
+    calls between multiple vendors. It allows multiple drivers from different
+    vendors to coexist on the same filesystem, and determines which vendor to
+    dispatch each API call to at runtime.
+
+    Both GLX and EGL are supported, in any combination with OpenGL and OpenGL
+    ES."""
+
+    homepage = "https://github.com/NVIDIA/libglvnd"
+    url      = "https://github.com/NVIDIA/libglvnd/releases/download/v1.1.1/libglvnd-1.1.1.tar.gz"
+    git      = "https://github.com/NVIDIA/libglvnd.git"
+
+    version('master', branch='master')
+
+    version('1.1.1', sha256='71918ed1261e4eece18c0b74b50dc62c0237b8d526e83277ef078554544720b9')
+
+    conflicts('platform=darwin', msg='libglvnd is linux specific')
+    conflicts('platform=bgq', msg='libglvnd is linux specific')
+
+    depends_on('libxext')
+    depends_on('libx11')
+    depends_on('glproto')
+
+    @when('@master')
+    def autoreconf(self, spec, prefix):
+        autogen = Executable('./autogen.sh')
+        autogen()
+
+    def configure_args(self):
+        return [
+            '--enable-egl',
+            '--enable-gles',
+            '--enable-glx'
+        ]