Unify csr and crt san writing functions

Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index 8e70c46..895805f 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -98,6 +98,7 @@
     x509_crl.c
     x509_crt.c
     x509_csr.c
+    x509write.c
     x509write_crt.c
     x509write_csr.c
 )