Fix parallel build race condition in Spack package

Fortran modules must be compiled sequentially to ensure
m_thermochem.mod is generated before m_derived_types.fpp
attempts to use it.

This fixes the build error:
  Fatal Error: Cannot open module file 'm_thermochem.mod'
  for reading at (1): No such file or directory

Setting parallel = False forces make -j1 to avoid race conditions.

Author: sbryngelson

packaging/spack/package.py

@@ -70,6 +70,9 @@ class Mfc(CMakePackage):
         "+openmp", when="+openacc", msg="OpenACC and OpenMP GPU offload are mutually exclusive"
     )
 
+    # Disable parallel builds to avoid Fortran module dependency race conditions
+    parallel = False
+
     def cmake_args(self):
         args = [
             self.define_from_variant("MFC_MPI", "mpi"),