meson: Reduce strength of oem-ibm requirements from enabled to allowed

If it's not expressly disabled, do what's necessary to build the oem-ibm
pieces of the code-base. Capture the newly-enabled APIs in the ABI
dumps.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: I50168309432620e03f00a4620b6bfc38f2e575c8
diff --git a/tests/meson.build b/tests/meson.build
index c41d8d2..78d65ee 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -26,7 +26,7 @@
   'msgbuf',
 ]
 
-if get_option('oem-ibm').enabled()
+if get_option('oem-ibm').allowed()
   tests += [
     'oem/ibm/libpldm_fileio_test',
     'oem/ibm/libpldm_host_test',