openblas : fix install_name on macos (#45606)

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

@@ -590,7 +590,12 @@ def check_install(self):
 
 class CMakeBuilder(spack.build_systems.cmake.CMakeBuilder):
     def cmake_args(self):
-        cmake_defs = [self.define("TARGET", "GENERIC")]
+        cmake_defs = [
+            self.define("TARGET", "GENERIC"),
+            # ensure MACOSX_RPATH is set
+            self.define("CMAKE_POLICY_DEFAULT_CMP0042", "NEW"),
+        ]
+
         if self.spec.satisfies("+dynamic_dispatch"):
             cmake_defs += [self.define("DYNAMIC_ARCH", "ON")]
         if self.spec.satisfies("platform=windows"):