omega-h: fix CMAKE_BUILD_TYPE: breaks with spack deafult 'RelWithDebInfo' (#10297)

var/spack/repos/builtin/packages/omega-h/package.py

@@ -78,6 +78,8 @@ def cmake_args(self):
             args.append('-DOmega_h_THROW:BOOL=ON')
         else:
             args.append('-DOmega_h_THROW:BOOL=OFF')
+        # omega-h requires empty CMAKE_BUILD_TYPE
+        args.append('-DCMAKE_BUILD_TYPE:STRING=')
         args += list(self._bob_options())
         return args