fcm build: fix fortran interface generation

Configuration logic was broken by metomi#156.

lib/FCM1/BuildSrc.pm

@@ -407,7 +407,7 @@ sub exebase {
 sub interfacebase {
   my $self = shift();
   if (
-        $self->get_setting(qw/TOOL GENINTERFACE/)
+        defined($self->get_setting(qw/TOOL GENINTERFACE/))
     &&  uc($self->get_setting(qw/TOOL GENINTERFACE/)) ne 'NONE'
     &&  $self->progname()
     &&  $self->is_type_all(qw/SOURCE/)

lib/FCM1/CfgFile.pm

@@ -241,7 +241,7 @@ sub read_cfg {
       }
     }
 
-    if (    $self->type()
+    if (    defined($self->type())
         &&  exists($exp_inc{uc($self->type())})
         &&  uc($start ? $start->label() : $label) eq $self->cfglabel('INC')
         &&  !defined($cont)

t/fcm-build/00-geninterface.t

@@ -0,0 +1,52 @@
+#!/bin/bash
+#-------------------------------------------------------------------------------
+# (C) British Crown Copyright 2006-14 Met Office.
+#
+# This file is part of FCM, tools for managing and building source code.
+#
+# FCM is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# FCM is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with FCM. If not, see <http://www.gnu.org/licenses/>.
+#-------------------------------------------------------------------------------
+# #156 breaks interface generation. This test ensures that it is not broken
+# again.
+#-------------------------------------------------------------------------------
+. "$(dirname "$0")/test_header"
+tests 2
+#-------------------------------------------------------------------------------
+
+cat >'bld.cfg' <<'__FCM_BLD_CFG__'
+cfg::type bld
+dest $HERE
+tool::geninterface
+__FCM_BLD_CFG__
+
+mkdir 'src'
+cat >'src/hello.f90' <<'__FORTRAN__'
+subroutine hello(world)
+character(*), intent(in) :: world
+write(*, '(a)') 'Hello ' // trim(world)
+end subroutine hello
+__FORTRAN__
+
+#-------------------------------------------------------------------------------
+run_pass "${TEST_KEY_BASE}-cmd" fcm build -f -s 4
+file_cmp "${TEST_KEY_BASE}-interface" 'inc/hello.interface' <<'__FORTRAN__'
+interface
+subroutine hello(world)
+character(*), intent(in) :: world
+end subroutine hello
+end interface
+__FORTRAN__
+
+#-------------------------------------------------------------------------------
+exit

t/fcm-build/test_header

@@ -0,0 +1 @@
+../lib/bash/test_header