tests: make sure CRLFs can't be used in URLs passed to proxy

Bug: http://curl.haxx.se/docs/adv_20150108B.html

tests/data/test1529

@@ -0,0 +1,43 @@
+<testcase>
+<info>
+<keywords>
+HTTP
+HTTP GET
+HTTP proxy
+</keywords>
+</info>
+
+# Server-side
+<reply>
+<connect>
+HTTP/1.1 200 OK
+We-are: good
+
+</connect>
+
+</reply>
+# Client-side
+<client>
+<server>
+http
+http-proxy
+</server>
+<tool>
+lib1529
+</tool>
+ <name>
+HTTP request-injection in URL sent over proxy
+ </name>
+ <command>
+ "http://the.old.moo:%HTTPPORT/1529" %HOSTIP:%PROXYPORT
+</command>
+</client>
+
+# it should be detected and an error should be reported
+<verify>
+# 3 == CURLE_URL_MALFORMAT
+<errorcode>
+3
+</errorcode>
+</verify>
+</testcase>