REGTESTS: add a basic reg-test for some "set-var" commands

This reg-test tests "set-var" in the global section, with some overlapping
variables and using a few samples and converters, then at the TCP and HTTP
levels using proc/sess/req variables.
diff --git a/reg-tests/sample_fetches/vars.vtc b/reg-tests/sample_fetches/vars.vtc
new file mode 100644
index 0000000..1461068
--- /dev/null
+++ b/reg-tests/sample_fetches/vars.vtc
@@ -0,0 +1,51 @@
+varnishtest "Test a few set-var() in global, tcp and http rule sets, at different scopes"
+#REQUIRE_VERSION=2.4
+
+feature ignore_unknown_macro
+
+haproxy h1 -conf {
+    global
+        set-var proc.int12 int(12)
+        set-var proc.int5  str(60),div(proc.int12)
+        set-var proc.str   str("this is")
+        set-var proc.str   str(""),concat("",proc.str," a string")
+        set-var proc.uuid  uuid()
+
+    defaults
+        mode http
+        timeout connect 1s
+        timeout client  1s
+        timeout server  1s
+
+    frontend fe1
+        bind "fd@${fe1}"
+        tcp-request session set-var(sess.int5) var(proc.int5)
+        tcp-request session set-var(proc.int5) var(proc.int5),add(sess.int5) ## proc. becomes 10
+        http-request set-var(req.int5)  var(sess.int5)
+        http-request set-var(sess.int5) var(sess.int5),add(req.int5) ## sess. becomes 10 first time, then 15...
+	http-request return status 200 hdr x-var "proc=%[var(proc.int5)] sess=%[var(sess.int5)] req=%[var(req.int5)] str=%[var(proc.str)] uuid=%[var(proc.uuid)]"
+} -start
+
+client c1 -connect ${h1_fe1_sock} {
+    txreq -req GET -url /req1_1
+    rxresp
+    expect resp.status == 200
+    expect resp.http.x-var ~ "proc=10 sess=10 req=5 str=this is a string uuid=[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*"
+
+    txreq -req GET -url /req1_2
+    rxresp
+    expect resp.status == 200
+    expect resp.http.x-var ~ "proc=10 sess=20 req=10 str=this is a string uuid=[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*"
+} -run
+
+client c2 -connect ${h1_fe1_sock} {
+    txreq -req GET -url /req2_1
+    rxresp
+    expect resp.status == 200
+    expect resp.http.x-var ~ "proc=20 sess=20 req=10 str=this is a string uuid=[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*"
+
+    txreq -req GET -url /req2_2
+    rxresp
+    expect resp.status == 200
+    expect resp.http.x-var ~ "proc=20 sess=40 req=20 str=this is a string uuid=[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*-[0-9a-f]*"
+} -run