test650: Use variable replacement to set the host address and port

Otherwise, the test fails when the -b test option is used to set a
different test port range.

tests/data/test650

@@ -57,7 +57,7 @@ s/boundary=------------------------[a-z0-9]*/boundary=--------------------------
 # (5*12) == 60 bytes less
 <protocol>
 POST /650 HTTP/1.1
-Host: 127.0.0.1:8990
+Host: %HOSTIP:%HTTPPORT
 Accept: */*
 Transfer-Encoding: chunked
 Content-Type: multipart/form-data; boundary=----------------------------