vdt: add preload variant (#30030)

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

@@ -18,6 +18,9 @@ class Vdt(CMakePackage):
     version('0.3.7', sha256='713a7e6d76d98f3b2b56b5216e7d5906e30f17865a5c7c889968e9a0b0664949')
     version('0.3.6', sha256='fb8f6386f2cd1eeb03db43f2b5c83a172107949bb5e5e8d4dfa603660a9757b0')
 
+    variant('preload', default=False,
+            description='Create in the library the symbols to preload the library')
+
     @property
     def build_directory(self):
         d = join_path(self.stage.path, 'spack-build')
@@ -40,4 +43,6 @@ def cmake_args(self):
                 f.upper(),
                 f not in disable_features and f in self.spec.target
             ))
+
+        options.append(self.define_from_variant('PRELOAD'))
         return options