/*D
   MPI_Is_thread_main - Returns a flag indicating whether this thread called 'MPI_Init' or 'MPI_Init_thread'

Synopsis:
.vb
int MPI_Is_thread_main(int *flag)
.ve

Output Parameters:
. flag - true if calling thread is main thread, false otherwise (logical)

.N ThreadSafe

.N Fortran

.N Errors
.N MPI_SUCCESS
.N MPI_ERR_ARG
.N MPI_ERR_OTHER

D*/

