build: use allowed over enabled

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`.

Change-Id: I816b3334e4bb65384a49bc34af6ae5fe092c923e
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/test/meson.build b/test/meson.build
index 2513278..50f71a3 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -80,7 +80,7 @@
                            swampd_sources,
                        ],
                        link_args: dynamic_linker,
-                       build_rpath: get_option('oe-sdk').enabled() ? rpath : '',
+                       build_rpath: get_option('oe-sdk').allowed() ? rpath : '',
                        dependencies: [
                            gtest,
                            gmock,