Make lam_mpi_initialized and lam_mpi_finalized be bool, not int

This commit was SVN r589.

src/mpi/runtime/lam_mpi_globals.c

@@ -8,5 +8,5 @@
  * Global variables and symbols for the MPI layer
  */
 
-int lam_mpi_initialized = 0;
-int lam_mpi_finalized = 0;
+bool lam_mpi_initialized = false;
+bool lam_mpi_finalized = false;