Fastcgi: fixed padding handling on fixed-size records.

Padding was incorrectly ignored on end request, empty stdout and stderr
fastcgi records.  This resulted in protocol desynchronization if fastcgi
application used these records with padding for some reason.

Reported by Ilia Vinokurov.

src/http/modules/ngx_http_fastcgi_module.c

diff --git a/src/http/modules/ngx_http_fastcgi_module.c b/src/http/modules/ngx_http_fastcgi_module.c
index 65f0747..55c3aef 100644
--- a/src/http/modules/ngx_http_fastcgi_module.c
+++ b/src/http/modules/ngx_http_fastcgi_module.c
@@ -1356,7 +1356,11 @@
                 }
 
             } else {
-                f->state = ngx_http_fastcgi_st_version;
+                if (f->padding) {
+                    f->state = ngx_http_fastcgi_st_padding;
+                } else {
+                    f->state = ngx_http_fastcgi_st_version;
+                }
             }
 
             continue;
@@ -1689,7 +1693,12 @@
             }
 
             if (f->type == NGX_HTTP_FASTCGI_STDOUT && f->length == 0) {
-                f->state = ngx_http_fastcgi_st_version;
+
+                if (f->padding) {
+                    f->state = ngx_http_fastcgi_st_padding;
+                } else {
+                    f->state = ngx_http_fastcgi_st_version;
+                }
 
                 if (!flcf->keep_conn) {
                     p->upstream_done = 1;
@@ -1702,7 +1711,13 @@
             }
 
             if (f->type == NGX_HTTP_FASTCGI_END_REQUEST) {
-                f->state = ngx_http_fastcgi_st_version;
+
+                if (f->padding) {
+                    f->state = ngx_http_fastcgi_st_padding;
+                } else {
+                    f->state = ngx_http_fastcgi_st_version;
+                }
+
                 p->upstream_done = 1;
 
                 if (flcf->keep_conn) {
@@ -1775,7 +1790,11 @@
                 }
 
             } else {
-                f->state = ngx_http_fastcgi_st_version;
+                if (f->padding) {
+                    f->state = ngx_http_fastcgi_st_padding;
+                } else {
+                    f->state = ngx_http_fastcgi_st_version;
+                }
             }
 
             continue;