Add library/*_internal.h to build files

Build scripts modified to refer to all internal headers being in
`library/*_internal.h`.

Signed-off-by: Chris Jones <christopher.jones@arm.com>
diff --git a/tests/scripts/list-identifiers.sh b/tests/scripts/list-identifiers.sh
index a52207e..b8a6d53 100755
--- a/tests/scripts/list-identifiers.sh
+++ b/tests/scripts/list-identifiers.sh
@@ -47,9 +47,9 @@
 
 if [ $INTERNAL ]
 then
-    HEADERS=$( ls include/mbedtls/*_internal.h library/*.h | egrep -v 'bn_mul' )
+    HEADERS=$( ls library/*.h )
 else
-    HEADERS=$( ls include/mbedtls/*.h include/psa/*.h library/*.h | egrep -v 'bn_mul' )
+    HEADERS=$( ls include/mbedtls/*.h include/psa/*.h library/*.h )
     HEADERS="$HEADERS 3rdparty/everest/include/everest/everest.h 3rdparty/everest/include/everest/x25519.h"
 fi