Fix compilation on Windows, and various Windows related mistakes introduced by

"safe exception patch".
Remove misleading comments suggesting about signal() Windows, the routine here
is part of a exception handler, and sig parameter is an exception code.

sql/signal_handler.cc

@@ -28,7 +28,7 @@
 #endif
 
 /*
-  We are handling signals in this file.
+  We are handling signals/exceptions in this file.
   Any global variables we read should be 'volatile sig_atomic_t'
   to guarantee that we read some consistent value.
  */
@@ -40,20 +40,18 @@ extern volatile sig_atomic_t ld_assume_kernel_is_set;
 #endif
 
 /**
- * Handler for fatal signals
+ * Handler for fatal signals on POSIX, exception handler on Windows.
  *
  * Fatal events (seg.fault, bus error etc.) will trigger
  * this signal handler.  The handler will try to dump relevant
  * debugging information to stderr and dump a core image.
  *
- * Signal handlers can only use a set of 'safe' system calls
- * and library functions.  A list of safe calls in POSIX systems
+ * POSIX : Signal handlers should, if possible, only use a set of 'safe' system 
+ * calls and library functions.  A list of safe calls in POSIX systems
  * are available at:
  *  http://pubs.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_04.html
- * For MS Windows, guidelines are available at:
- *  http://msdn.microsoft.com/en-us/library/xdkz3x12(v=vs.71).aspx
  *
- * @param sig Signal number
+ * @param sig Signal number /Exception code
 */
 extern "C" sig_handler handle_fatal_signal(int sig)
 {
@@ -77,7 +75,13 @@ extern "C" sig_handler handle_fatal_signal(int sig)
   my_safe_printf_stderr("%02d%02d%02d %2d:%02d:%02d ",
                         tm.tm_year % 100, tm.tm_mon+1, tm.tm_mday,
                         tm.tm_hour, tm.tm_min, tm.tm_sec);
-  if (opt_expect_abort && sig == SIGABRT)
+  if (opt_expect_abort
+#ifdef _WIN32
+    && sig == EXCEPTION_BREAKPOINT /* __debugbreak in my_sigabrt_hander() */
+#else
+    && sig == SIGABRT
+#endif
+    )
   {
     fprintf(stderr,"[Note] mysqld did an expected abort\n");
     goto end;
@@ -252,5 +256,7 @@ extern "C" sig_handler handle_fatal_signal(int sig)
      On Windows, do not terminate, but pass control to exception filter.
   */
   _exit(1);  // Using _exit(), since exit() is not async signal safe
+#else
+  return;
 #endif
 }