Enable OpenMP by default in CMake call

setup.py

@@ -94,10 +94,15 @@ def run(self):
         build_type = os.getenv("PYBAMM_CPP_BUILD_TYPE", "RELEASE")
         idaklu_expr_casadi = os.getenv("PYBAMM_IDAKLU_EXPR_CASADI", "ON")
         idaklu_expr_iree = os.getenv("PYBAMM_IDAKLU_EXPR_IREE", "OFF")
+        # OpenMP is enabled by default, we'll disable it for WASM builds
+        pybamm_openmp = (
+            "OFF" if os.getenv("PYODIDE") else os.getenv("PYBAMM_OPENMP", "ON")
+        )
         cmake_args = [
             f"-DCMAKE_BUILD_TYPE={build_type}",
             f"-DPYTHON_EXECUTABLE={sys.executable}",
             "-DUSE_PYTHON_CASADI={}".format("TRUE" if use_python_casadi else "FALSE"),
+            f"-DPYBAMM_OPENMP={pybamm_openmp}",
             f"-DPYBAMM_IDAKLU_EXPR_CASADI={idaklu_expr_casadi}",
             f"-DPYBAMM_IDAKLU_EXPR_IREE={idaklu_expr_iree}",
         ]