Add a new file for constant-time functions

Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index a69e733..0cafd88 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -26,6 +26,7 @@
     chachapoly.c
     cipher.c
     cipher_wrap.c
+    constant_time.c
     cmac.c
     ctr_drbg.c
     des.c