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/mysqld.cc

@@ -119,6 +119,8 @@
 
 #include <my_service_manager.h>
 
+#include <source_revision.h>
+
 #define mysqld_charset &my_charset_latin1
 
 /* We have HAVE_valgrind below as this speeds up the shutdown of MySQL */
@@ -4445,21 +4447,6 @@ static int init_common_variables()
 
   mysql_real_data_home_len= uint(strlen(mysql_real_data_home));
 
-  if (!opt_abort)
-  {
-    if (IS_SYSVAR_AUTOSIZE(&server_version_ptr))
-      sql_print_information("%s (mysqld %s) starting as process %lu ...",
-                            my_progname, server_version, (ulong) getpid());
-    else
-    {
-      char real_server_version[SERVER_VERSION_LENGTH];
-      set_server_version(real_server_version, sizeof(real_server_version));
-      sql_print_information("%s (mysqld %s as %s) starting as process %lu ...",
-                            my_progname, real_server_version, server_version,
-                            (ulong) getpid());
-    }
-  }
-
   sf_leaking_memory= 0; // no memory leaks from now on
 
 #ifndef EMBEDDED_LIBRARY
@@ -5258,6 +5245,13 @@ static int init_server_components()
   error_handler_hook= my_message_sql;
   proc_info_hook= set_thd_stage_info;
 
+  /*
+    Print source revision hash, as one of the first lines, if not the
+    first in error log, for troubleshooting and debugging purposes
+  */
+  sql_print_information("Starting MariaDB %s source revision %s as process %lu",
+		         server_version, SOURCE_REVISION, (ulong) getpid());
+
 #ifdef WITH_PERFSCHEMA_STORAGE_ENGINE
   /*
     Parsing the performance schema command line option may have reported

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",