[MINOR] acl: add REQ_CONTENT to the list of default acls

With content inspection, checking the presence of data in the
request buffer is very important. It's getting boring to always
add such an ACL, so let's add it by default.

doc/configuration.txt

@@ -3956,6 +3956,7 @@ HTTP_URL_ABS     url_reg ^[^/:]*://            match absolute URL with scheme
 HTTP_URL_SLASH   url_beg /                     match URL begining with "/"
 HTTP_URL_STAR    url     *                     match URL equal to "*"
 HTTP_CONTENT     hdr_val(content-length) gt 0  match an existing content-length
+REQ_CONTENT      req_len gt 0                  match data in the request buffer
 ---------------+-----------------------------+---------------------------------
 
 

src/acl.c

@@ -758,6 +758,7 @@ const struct {
 	{ .name = "HTTP_URL_SLASH", .expr = {"url_beg","/",""}},
 	{ .name = "HTTP_URL_STAR",  .expr = {"url","*",""}},
 	{ .name = "HTTP_CONTENT",   .expr = {"hdr_val(content-length)","gt","0",""}},
+	{ .name = "REQ_CONTENT",    .expr = {"req_len","gt","0",""}},
 	{ .name = NULL, .expr = {""}}
 };