Always build glib with iconv (#10219)

* Always build glib with iconv

My early PR, #10165, which added a variant to configure glib to use
libiconv and defaulted to false, seems to be causing more trouble than
the knob is worth.

This changes the glib package to always depend on and use libiconv.

* libiconv depends_on is no longer conditional

var/spack/repos/builtin/packages/glib/package.py

@@ -32,7 +32,6 @@ class Glib(AutotoolsPackage):
     version('2.48.1', '67bd3b75c9f6d5587b457dc01cdcd5bb')
     version('2.42.1', '89c4119e50e767d3532158605ee9121a')
 
-    variant('iconv', default=False, description='Build with iconv support')
     variant('libmount', default=False, description='Build with libmount support')
     variant(
         'tracing',
@@ -50,7 +49,7 @@ class Glib(AutotoolsPackage):
     depends_on('python', type=('build', 'run'), when='@2.53.4:')
     depends_on('pcre+utf', when='@2.48:')
     depends_on('util-linux', when='+libmount')
-    depends_on('libiconv', when='+iconv')
+    depends_on('libiconv')
 
     # The following patch is needed for gcc-6.1
     patch('g_date_strftime.patch', when='@2.42.1')
@@ -74,10 +73,7 @@ def configure_args(self):
             args.append('--with-python={0}'.format(
                 os.path.basename(self.spec['python'].command.path))
             )
-        if self.spec.satisfies('+iconv'):
-            args.append('--with-libiconv=gnu')
-        else:
-            args.append('--with-libiconv=no')
+        args.append('--with-libiconv=gnu')
         args.extend(self.enable_or_disable('tracing'))
         # SELinux is not available in Spack, so glib should not use it.
         args.append('--disable-selinux')