Add the working testcase from PR fortran/39290.

testsuite/
	PR fortran/39290
	* gfortran.dg/interface_37.f90: New test.

From-SVN: r190504

gcc/testsuite/ChangeLog

+2012-08-18  Mikael Morin  <mikael@gcc.gnu.org>
+
+	PR fortran/39290
+	* gfortran.dg/interface_37.f90: New test.
+
 2012-08-17  H.J. Lu  <hongjiu.lu@intel.com>
 	    Gary Funck <gary@intrepid.com>
 

gcc/testsuite/gfortran.dg/interface_37.f90

+! { dg-do compile }
+!
+! PR fortran/39290
+! Subroutine/function ambiguity in generics.
+!
+     interface q
+       subroutine qr(f)
+         implicit real(f)
+         external f
+       end subroutine
+       subroutine qc(f)
+         implicit complex(f)
+         external f
+       end subroutine ! { dg-error "Ambiguous interfaces" }
+     end interface q
+   end