build: use allowed over enabled or not-disabled

Meson feature options are typically in a tri-state of enabled, disabled,
or auto.  The enabled and disabled functions on an option (from
`get_option`) no longer return true for auto features.  Instead, the
expectation is to use `allowed()` which is true for both enabled and
auto.

Switch all uses of `enabled` to `allowed`.
Switch all uses of `not disabled` to `allowed`.

Change-Id: I3e26b283457a6442d20adeca3f40bf0269009a3c
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/meson.build b/meson.build
index a4b5281..03f3031 100644
--- a/meson.build
+++ b/meson.build
@@ -37,7 +37,7 @@
 config_data.set('authority_limit', get_option('authority-limit'))
 config_data.set('authorities_list_name', get_option('authorities-list-name'))
 
-if not get_option('allow-expired').disabled()
+if get_option('allow-expired').allowed()
     config_data.set('allow_expired', 'true')
 else
     config_data.set('allow_expired', 'false')
@@ -83,13 +83,13 @@
     install: true,
 )
 
-if not get_option('ca-cert-extension').disabled()
+if get_option('ca-cert-extension').allowed()
     subdir('bmc-vmi-ca')
 endif
 
 subdir('dist')
 
-if not get_option('tests').disabled()
+if get_option('tests').allowed()
     subdir('test')
 endif