build: fix option selection

By default, meson will set a feature option to `auto`, which
is suppose to be effectively enabled.  Multiple places in this
repository's meson.build use `if option.enabled` instead of `if
option.allowed`, which means that only an explicit `enabled` setting
actually enables the feature.  This is not desired and limits the
amount of testing we see in CI.  Switch them to enable the feature
if either `enabled` or `auto` (by using `allowed`).

Change-Id: I977557b35af7c7d0a880b20cbd09a2f29e1c7fe4
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/meson.build b/meson.build
index 56cb156..5139e3e 100644
--- a/meson.build
+++ b/meson.build
@@ -124,7 +124,7 @@
                  'vpd-parser/ipz_parser.cpp', 'impl.cpp', 'ibm_vpd_utils.cpp',
 ]
 
-if get_option('ibm-parser').enabled()
+if get_option('ibm-parser').allowed()
         libgpiodcxx = dependency(
             'libgpiodcxx',
             default_options: ['bindings=cxx'],
@@ -172,7 +172,7 @@
                                  include_directories : vpd_tool_INCLUDE,
                                  cpp_args : '-DIPZ_PARSER'
                                  )
-if get_option('vpd-manager').enabled()
+if get_option('vpd-manager').allowed()
     subdir('vpd-manager')
 endif