src: add 'size_delivered' as a write-out variable

Verify in test 220

docs/cmdline-opts/write-out.md

@@ -193,6 +193,10 @@ known as "http_code"). (Added in 7.18.2)
 ## `scheme`
 The URL scheme (sometimes called protocol) that was effectively used. (Added in 7.52.0)
 
+## `size_delivered`
+The total amount of data that were saved or written to stdout. When
+--compressed is used, this could very well be different than `size_download`.
+
 ## `size_download`
 The total amount of bytes that were downloaded. This is the size of the
 body/data that was transferred, excluding headers.

src/tool_writeout.c

@@ -461,6 +461,8 @@ static const struct writeoutvar variables[] = {
   { "remote_port", VAR_PRIMARY_PORT, CURLINFO_PRIMARY_PORT, writeLong },
   { "response_code", VAR_HTTP_CODE, CURLINFO_RESPONSE_CODE, writeLong },
   { "scheme", VAR_SCHEME, CURLINFO_SCHEME, writeString },
+  { "size_delivered", VAR_SIZE_DELIVERED, CURLINFO_SIZE_DELIVERED,
+    writeOffset },
   { "size_download", VAR_SIZE_DOWNLOAD, CURLINFO_SIZE_DOWNLOAD_T,
     writeOffset },
   { "size_header", VAR_HEADER_SIZE, CURLINFO_HEADER_SIZE, writeLong },

src/tool_writeout.h

@@ -90,6 +90,7 @@ typedef enum {
   VAR_REFERER,
   VAR_REQUEST_SIZE,
   VAR_SCHEME,
+  VAR_SIZE_DELIVERED,
   VAR_SIZE_DOWNLOAD,
   VAR_SIZE_UPLOAD,
   VAR_SPEED_DOWNLOAD,

tests/data/test220

@@ -50,7 +50,7 @@ http
 HTTP GET gzip compressed content
 </name>
 <command>
-http://%HOSTIP:%HTTPPORT/%TESTNUMBER --compressed
+http://%HOSTIP:%HTTPPORT/%TESTNUMBER --compressed -s -w '%{stderr}%{size_delivered}\n'
 </command>
 </client>
 
@@ -67,5 +67,8 @@ Accept: */*
 Accept-Encoding: xxx
 
 </protocol>
+<stderr>
+24
+</stderr>
 </verify>
 </testcase>