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: I794c658531483266bfce6f9b28127a166ed01490
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/common/test/meson.build b/common/test/meson.build
index 9e5517e..3ad51a6 100644
--- a/common/test/meson.build
+++ b/common/test/meson.build
@@ -10,7 +10,7 @@
   test(t, executable(t.underscorify(), t + '.cpp',
                      implicit_include_directories: false,
                      link_args: dynamic_linker,
-                     build_rpath: get_option('oe-sdk').enabled() ? rpath : '',
+                     build_rpath: get_option('oe-sdk').allowed() ? rpath : '',
                      dependencies: [
                          common_test_src,
                          gtest,