nat: Allow to use the prefix lookup to rewrite numbers
* Increase the rewritten rule to five digits (this is the easiest
for the unit test). This will add another 40kb to the runtime size.
* Create a unit test that tests adding and removing the prefix rules.
* Use the regexp match to replace from one package
diff --git a/openbsc/tests/bsc-nat/prefixes.csv b/openbsc/tests/bsc-nat/prefixes.csv
new file mode 100644
index 0000000..0b66ffe
--- /dev/null
+++ b/openbsc/tests/bsc-nat/prefixes.csv
@@ -0,0 +1 @@
+0172,0049