Core: exit on ngx_pnalloc() failure.

Signed-off-by: Piotr Sikora <piotr@cloudflare.com>

src/os/unix/ngx_process_cycle.c

diff --git a/src/os/unix/ngx_process_cycle.c b/src/os/unix/ngx_process_cycle.c
index fb10d77..3205aa5 100644
--- a/src/os/unix/ngx_process_cycle.c
+++ b/src/os/unix/ngx_process_cycle.c
@@ -121,6 +121,10 @@
     }
 
     title = ngx_pnalloc(cycle->pool, size);
+    if (title == NULL) {
+        /* fatal */
+        exit(2);
+    }
 
     p = ngx_cpymem(title, master_process, sizeof(master_process) - 1);
     for (i = 0; i < ngx_argc; i++) {