MEDIUM: proxy: remove acl_requires and just keep a flag "http_needed"

Proxy's acl_requires was a copy of all bits taken from ACLs, but we'll
get rid of ACL flags and only rely on sample fetches soon. The proxy's
acl_requires was only used to allocate an HTTP context when needed, and
was even forced in HTTP mode. So better have a flag which exactly says
what it's supposed to be used for.
diff --git a/include/proto/acl.h b/include/proto/acl.h
index 58591ab..1471dae 100644
--- a/include/proto/acl.h
+++ b/include/proto/acl.h
@@ -84,8 +84,8 @@
 /* Builds an ACL condition starting at the if/unless keyword. The complete
  * condition is returned. NULL is returned in case of error or if the first
  * word is neither "if" nor "unless". It automatically sets the file name and
- * the line number in the condition for better error reporting, and adds the
- * ACL requirements to the proxy's acl_requires. If <err> is not NULL, it will
+ * the line number in the condition for better error reporting, and sets the
+ * HTTP initialization requirements in the proxy. If <err> is not NULL, it will
  * be set to an error message upon errors, that the caller will have to free.
  */
 struct acl_cond *build_acl_cond(const char *file, int line, struct proxy *px, const char **args, char **err);
diff --git a/include/types/proxy.h b/include/types/proxy.h
index 87e90ee..5abf35e 100644
--- a/include/types/proxy.h
+++ b/include/types/proxy.h
@@ -205,6 +205,7 @@
 	unsigned int fe_req_ana, be_req_ana;	/* bitmap of common request protocol analysers for the frontend and backend */
 	unsigned int fe_rsp_ana, be_rsp_ana;	/* bitmap of common response protocol analysers for the frontend and backend */
 	int mode;				/* mode = PR_MODE_TCP, PR_MODE_HTTP or PR_MODE_HEALTH */
+	unsigned int http_needed;               /* non-null if HTTP analyser may be used */
 	union {
 		struct proxy *be;		/* default backend, or NULL if none set */
 		char *name;			/* default backend name during config parse */
@@ -227,7 +228,6 @@
 		unsigned int inspect_delay;     /* inspection delay */
 		struct list inspect_rules;      /* inspection rules */
 	} tcp_rep;
-	int acl_requires;                       /* Elements required to satisfy all ACLs (ACL_USE_*) */
 	struct server *srv, defsrv;		/* known servers; default server configuration */
 	int srv_act, srv_bck;			/* # of servers eligible for LB (UP|!checked) AND (enabled+weight!=0) */
 	struct lbprm lbprm;			/* load-balancing parameters */