Native fetcher crashes

[oschaaf]

Looks like this happens when running out of file descriptors.
I noticed this will stress testing the single fd patch.

Backtrace:

#0  net_instaweb::NgxFetch::Connect (this=0x7fffe808cc80) at /home/oschaaf/code/google/ngx_pagespeed/src/ngx_fetch.cc:417
#1  0x0000000000473354 in net_instaweb::NgxFetch::InitRequest (this=0x7fffe808cc80) at /home/oschaaf/code/google/ngx_pagespeed/src/ngx_fetch.cc:391
#2  0x000000000047386d in net_instaweb::NgxFetch::Init (this=0x7fffe808cc80) at /home/oschaaf/code/google/ngx_pagespeed/src/ngx_fetch.cc:177
#3  0x0000000000473924 in net_instaweb::NgxFetch::Start (this=<optimized out>, fetcher=<optimized out>) at /home/oschaaf/code/google/ngx_pagespeed/src/ngx_fetch.cc:92
#4  0x000000000048027a in net_instaweb::NgxUrlAsyncFetcher::StartFetch (this=0xe7a650, fetch=0x7fffe808cc80)
    at /home/oschaaf/code/google/ngx_pagespeed/src/ngx_url_async_fetcher.cc:298
#5  0x000000000048070a in net_instaweb::NgxUrlAsyncFetcher::CommandHandler (cmdev=0xee3780) at /home/oschaaf/code/google/ngx_pagespeed/src/ngx_url_async_fetcher.cc:256
#6  0x000000000042b4d9 in ngx_epoll_process_events (cycle=<optimized out>, timer=<optimized out>, flags=<optimized out>) at src/event/modules/ngx_epoll_module.c:683
#7  0x0000000000423fd7 in ngx_process_events_and_timers (cycle=0xe64490) at src/event/ngx_event.c:249
#8  0x000000000042ae36 in ngx_single_process_cycle (cycle=0xe64490) at src/os/unix/ngx_process_cycle.c:315
#9  0x000000000040f179 in main (argc=<optimized out>, argv=<optimized out>) at src/core/nginx.c:409

[oschaaf]

Fixed in #465