check-names: Consider crypto-sourced header files

Many identifiers come from Mbed Crypto. Teach check-names.sh to look in
the crypto submodule for identifiers, to avoid incorrect test results.
diff --git a/tests/scripts/list-macros.sh b/tests/scripts/list-macros.sh
index 3c84adb..4ef0574 100755
--- a/tests/scripts/list-macros.sh
+++ b/tests/scripts/list-macros.sh
@@ -7,7 +7,7 @@
     exit 1
 fi
 
-HEADERS=$( ls include/mbedtls/*.h | egrep -v 'compat-1\.3\.h' )
+HEADERS=$( ls include/mbedtls/*.h crypto/include/mbedtls/*.h | egrep -v 'compat-1\.3\.h' )
 
 sed -n -e 's/.*#define \([a-zA-Z0-9_]*\).*/\1/p' $HEADERS \
     | egrep -v '^(asm|inline|EMIT|_CRT_SECURE_NO_DEPRECATE)$|^MULADDC_' \