This patch is pretty self-explanatory. I have checked that a sensible
errors are given if 'exfunc' in the testcase is referenced if it is a
variable.

Bootstrapped and regtested on FC29/x86_64 - OK for trunk?

Paul

2019-03-30  Paul Thomas  <pault@gcc.gnu.org>

    PR fortran/87127
    * resolve.c (check_host_association): If an external function
    is typed but not declared explicitly to be external, change the
    old symbol from a variable to an external function.

2019-03-30  Paul Thomas  <pault@gcc.gnu.org>

    PR fortran/87127
    * gfortran.dg/external_procedures_4.f90: New test.