Python: Add weak crypto key example through function call

We used to handle this, but no more :(

Adding this example was inspired by looking at results differences

Author: RasmusWL

python/ql/test/query-tests/Security/CWE-326/weak_crypto.py

@@ -75,3 +75,16 @@
 
 DSA.generate(DSA_WEAK)
 RSA.generate(RSA_WEAK)
+
+# ------------------------------------------------------------------------------
+
+# Through function calls
+
+def make_new_rsa_key_weak(bits):
+    return RSA.generate(bits) # NOT OK
+make_new_rsa_key_weak(RSA_WEAK)
+
+
+def make_new_rsa_key_strong(bits):
+    return RSA.generate(bits) # OK
+make_new_rsa_key_strong(RSA_STRONG)