BUILD: task: work around a bogus warning in gcc 4.7/4.8 at -O1

As reported in issue #816, when building task.o at -O1 with gcc 4.7 or
4.8, we get the following warning:

    CC      src/task.o
  In file included from include/haproxy/proxy.h:31:0,
                   from include/haproxy/cfgparse.h:27,
                   from src/task.c:19:
  src/task.c: In function 'next_timer_expiry':
  include/haproxy/ticks.h:121:10: warning: 'key' may be used uninitialized in this function [-Wmaybe-uninitialized]
  src/task.c:349:2: note: 'key' was declared here

It is wrong since the condition to use 'key' is exactly the same as
the one used to set it. This warning disappears at -O2 and disappeared
from gcc 5 and above. Let's just initialize 'key' there, it only adds
16 bytes of code and remains cheap enough for this function.

This should be backported to 2.2.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/task.c b/src/task.c
index c91316cbb..cabfcbe1e 100644
--- a/src/task.c
+++ b/src/task.c
@@ -346,7 +346,7 @@ int next_timer_expiry()
 	struct task_per_thread * const tt = sched; // thread's tasks
 	struct eb32_node *eb;
 	int ret = TICK_ETERNITY;
-	__decl_thread(int key);
+	__decl_thread(int key = TICK_ETERNITY);
 
 	/* first check in the thread-local timers */
 	eb = eb32_lookup_ge(&tt->timers, now_ms - TIMER_LOOK_BACK);