Fix ignored headers handling in fastcgi/scgi/uwsgi.

The bug had appeared in r3561 (fastcgi), r3638 (scgi), r3567 (uwsgi).

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 71194fd..0bc95f8 100644
--- a/src/http/modules/ngx_http_fastcgi_module.c
+++ b/src/http/modules/ngx_http_fastcgi_module.c
@@ -737,7 +737,15 @@
         lowcase_key = NULL;
 
         if (flcf->header_params) {
-            ignored = ngx_palloc(r->pool, flcf->header_params * sizeof(void *));
+            n = 0;
+            part = &r->headers_in.headers.part;
+
+            while (part) {
+                n += part->nelts;
+                part = part->next;
+            }
+
+            ignored = ngx_palloc(r->pool, n * sizeof(void *));
             if (ignored == NULL) {
                 return NGX_ERROR;
             }

src/http/modules/ngx_http_scgi_module.c

diff --git a/src/http/modules/ngx_http_scgi_module.c b/src/http/modules/ngx_http_scgi_module.c
index c83d770..a4230a9 100644
--- a/src/http/modules/ngx_http_scgi_module.c
+++ b/src/http/modules/ngx_http_scgi_module.c
@@ -561,7 +561,15 @@
         lowcase_key = NULL;
 
         if (scf->header_params) {
-            ignored = ngx_palloc(r->pool, scf->header_params * sizeof(void *));
+            n = 0;
+            part = &r->headers_in.headers.part;
+
+            while (part) {
+                n += part->nelts;
+                part = part->next;
+            }
+
+            ignored = ngx_palloc(r->pool, n * sizeof(void *));
             if (ignored == NULL) {
                 return NGX_ERROR;
             }

src/http/modules/ngx_http_uwsgi_module.c

diff --git a/src/http/modules/ngx_http_uwsgi_module.c b/src/http/modules/ngx_http_uwsgi_module.c
index a907e53..37b7632 100644
--- a/src/http/modules/ngx_http_uwsgi_module.c
+++ b/src/http/modules/ngx_http_uwsgi_module.c
@@ -589,7 +589,15 @@
         lowcase_key = NULL;
 
         if (uwcf->header_params) {
-            ignored = ngx_palloc(r->pool, uwcf->header_params * sizeof(void *));
+            n = 0;
+            part = &r->headers_in.headers.part;
+
+            while (part) {
+                n += part->nelts;
+                part = part->next;
+            }
+
+            ignored = ngx_palloc(r->pool, n * sizeof(void *));
             if (ignored == NULL) {
                 return NGX_ERROR;
             }