Fixed header parsing with ignore_invalid_headers switched off.

The parsing was broken when the first character of the header name was invalid.

Based on a patch by Alan Kemp.

src/http/ngx_http_parse.c

diff --git a/src/http/ngx_http_parse.c b/src/http/ngx_http_parse.c
index aa56b97..cfc42f9 100644
--- a/src/http/ngx_http_parse.c
+++ b/src/http/ngx_http_parse.c
@@ -912,6 +912,8 @@
                         i = 1;
 
                     } else {
+                        hash = 0;
+                        i = 0;
                         r->invalid_header = 1;
                     }
 
@@ -922,6 +924,8 @@
                     return NGX_HTTP_PARSE_INVALID_HEADER;
                 }
 
+                hash = 0;
+                i = 0;
                 r->invalid_header = 1;
 
                 break;