Add the x509_oid module to the build

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index a32b4bc..f896850 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -6,6 +6,7 @@
     x509_crl.c
     x509_crt.c
     x509_csr.c
+    x509_oid.c
     x509write.c
     x509write_crt.c
     x509write_csr.c