Fix build for scine-xtb (#35386)

var/spack/repos/builtin/packages/scine-utilities/package.py

@@ -67,7 +67,7 @@ def patch(self):
     def cmake_args(self):
         args = [
             self.define("SCINE_BUILD_TESTS", self.run_tests),
-            self.define("SCINE_BUILD_PYTHON_BINDINGS", "+python" in self.spec),
+            self.define_from_variant("SCINE_BUILD_PYTHON_BINDINGS", "python"),
             self.define("SCINE_MARCH", ""),
             self.define("BOOST_ROOT", self.spec["boost"].prefix),
             self.define("BOOST_LIBRARY_DIR", self.spec["boost"].libs.directories[0]),

var/spack/repos/builtin/packages/scine-xtb/package.py

@@ -25,6 +25,12 @@ class ScineXtb(CMakePackage):
         placement="_dev",
     )
 
+    patch(
+        "https://raw.githubusercontent.com/conda-forge/scine-xtb-feedstock/4ac2b70/recipe/patches/pkgconfig.patch",
+        level=1,
+        sha256="8650abf9dca269f62b60733aabfac0681d9d1cfd721bec728752fb4cbca44452",
+    )
+
     variant("python", default=False, description="Build Python extension module")
 
     depends_on("boost+system+filesystem+program_options cxxstd=17 @1.65.0:")