Fix usage of {curves,key-exchanges}.pl in all.sh
diff --git a/tests/scripts/curves.pl b/tests/scripts/curves.pl
index 1a05b40..90353d3 100755
--- a/tests/scripts/curves.pl
+++ b/tests/scripts/curves.pl
@@ -1,10 +1,28 @@
#!/usr/bin/perl
-# test dependencies on individual curves in tests
-# - build
-# - run test suite
+# curves.pl
+#
+# Copyright (c) 2014-2016, ARM Limited, All Rights Reserved
+#
+# Purpose
+#
+# To test the code dependencies on individual curves in each test suite. This
+# is a verification step to ensure we don't ship test suites that do not work
+# for some build options.
+#
+# The process is:
+# for each possible curve
+# build the library and test suites with the curve disabled
+# execute the test suites
+#
+# And any test suite with the wrong dependencies will fail.
#
# Usage: tests/scripts/curves.pl
+#
+# This script should be executed from the root of the project directory.
+#
+# For best effect, run either with cmake disabled, or cmake enabled in a mode
+# that includes -Werror.
use warnings;
use strict;