check-names: Update for deprecation tags

Make list-identifiers deal with deprecation tags by treating the
`MBEDTLS_DEPRECATED` attribute as an identifier. Treat
`MBEDTLS_DEPRECATED` the same as one would `struct` on a function that
returned a `struct` (e.g. `struct something do_action(int param)`)

tests/scripts/list-identifiers.sh

@@ -41,7 +41,7 @@ rm -f identifiers
 
 grep '^[^ /#{]' $HEADERS | \
     sed -e 's/^[^:]*://' | \
-    egrep -v '^(extern "C"|(typedef )?(struct|enum)( {)?$|};?$)' \
+    egrep -v '^(extern "C"|(typedef )?(struct|enum|MBEDTLS_DEPRECATED)( {)?$|};?$)' \
     > _decls
 
 if true; then