Print signal to stdout before calling crash handler

Doesn't fix anything but if deadlock described on the bug happens
locally and stdout is piped to console (or line-buffered file),
it's at least visible that a signal handler was invoked.

Bug: angleproject:8080
Change-Id: I27e1b22cc269082682fd639ef087f1b8b14b26eb
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4544588
Reviewed-by: Amirali Abdolrashidi <abdolrashidi@google.com>
Auto-Submit: Roman Lavrov <romanl@google.com>
Commit-Queue: Amirali Abdolrashidi <abdolrashidi@google.com>

util/posix/crash_handler_posix.cpp

@@ -126,12 +126,13 @@ void PrintStackBacktrace()
 
 static void Handler(int sig)
 {
+    printf("\nSignal %d:\n", sig);
+
     if (gCrashHandlerCallback)
     {
         (*gCrashHandlerCallback)();
     }
 
-    printf("\nSignal %d:\n", sig);
     PrintStackBacktrace();
 
     // Exit NOW.  Don't notify other threads, don't call anything registered with atexit().
@@ -645,12 +646,13 @@ void PrintStackBacktrace()
 
 static void Handler(int sig)
 {
+    printf("\nSignal %d [%s]:\n", sig, strsignal(sig));
+
     if (gCrashHandlerCallback)
     {
         (*gCrashHandlerCallback)();
     }
 
-    printf("\nSignal %d [%s]:\n", sig, strsignal(sig));
     PrintStackBacktrace();
 
     // Exit NOW.  Don't notify other threads, don't call anything registered with atexit().