MDEV-17093: SOURCE_REVISION in log and handle_fatal_signal

MariaDB MDEV-12583 added `SOURCE_REVISION` variable that exposes the
SHA1 of source code commit that the current running engine was built
from. This info is useful for troubleshooting and debugging.

This commit does the following:
- addes the `SOURCE_REVISION` value into engine error log.
- when a crash triggers handle_fatal_signal, the `SOURCE_REVISION` will
  be included in crash report.
- resolves MDEV-20344: startup messages belong in stderr/error-log not
  stdout

All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license.  I am contributing on behalf of my employer Amazon Web
Services, Inc.

sql/signal_handler.cc

@@ -22,6 +22,7 @@
 #include "mysqld.h"
 #include "sql_class.h"
 #include "my_stacktrace.h"
+#include <source_revision.h>
 
 #ifdef __WIN__
 #include <crtdbg.h>
@@ -177,7 +178,8 @@ extern "C" sig_handler handle_fatal_signal(int sig)
     "something is definitely wrong and this may fail.\n\n");
 
   set_server_version(server_version, sizeof(server_version));
-  my_safe_printf_stderr("Server version: %s\n", server_version);
+  my_safe_printf_stderr("Server version: %s source revision: %s\n",
+		        server_version, SOURCE_REVISION);
 
   if (dflt_key_cache)
     my_safe_printf_stderr("key_buffer_size=%lu\n",