REGTESTS: test case for map_regm commit 271022150d

Minimal test case for map_regm commit 271022150d7961b9aa39dbfd88e0c6a4bc48c3ee.
Config and test is adapted from: Daniel Schneller's example
(https://www.mail-archive.com/haproxy@formilux.org/msg30523.html).
diff --git a/reg-tests/http-rules/b00000.map b/reg-tests/http-rules/b00000.map
new file mode 100644
index 0000000..08ffcfb
--- /dev/null
+++ b/reg-tests/http-rules/b00000.map
@@ -0,0 +1 @@
+^(.*)\.(.*)$ \1_AND_\2