MDEV-20685: compile fixes for Solaris/OSX/AIX

sig_return: Solaris/OSX returns different function ptr
Move defination to my_alarm.h as its the only use.

prevents compile warnings (copied from 10.3 branch)

mysys/my_sync.c:136:19: error: 'cur_dir_name' defined but not used [-Werror=unused-const-variable=]
  136 | static const char cur_dir_name[]= {FN_CURLIB, 0};
      |                   ^~~~~~~~~~~~

fix compile error (DEPRECATED) leaked from ssl headers.

In file included from /export/home/dan/mariadb-server-10.4/sql/sys_vars.cc:37:
/export/home/dan/mariadb-server-10.4/sql/sys_vars.ic:69: error: "DEPRECATED" redefined [-Werror]
   69 | #define DEPRECATED(X) X
      |
In file included from /export/home/dan/mariadb-server-10.4/include/violite.h:150,
                 from /export/home/dan/mariadb-server-10.4/sql/sql_class.h:38,
                 from /export/home/dan/mariadb-server-10.4/sql/sys_vars.cc:36:
/usr/include/openssl/ssl.h:2356: note: this is the location of the previous definition
 2356 | # define DEPRECATED __attribute__((deprecated))
      |

Avoid Werror condition on non-Linux:

plugin/server_audit/server_audit.c:2267:7: error: variable 'db_len_off' set but not used [-Werror=unused-but-set-variable]
 2267 |   int db_len_off;
      |       ^~~~~~~~~~
plugin/server_audit/server_audit.c:2266:7: error: variable 'db_off' set but not used [-Werror=unused-but-set-variable]
 2266 |   int db_off;
      |       ^~~~~~

auth_gssapi fix include path for Solaris

Consistent with the upstream packaged patch:
https://github.com/OpenIndiana/oi-userland/blob/oi/hipster/components/database/mariadb-103/patches/06-gssapi.h.patch

compile warnings on Solaris

[ 91%] Building C object plugin/server_audit/CMakeFiles/server_audit.dir/server_audit.c.o
/plugin/server_audit/server_audit.c: In function 'auditing_v8':
/plugin/server_audit/server_audit.c:2194:20: error: unused variable 'db_len_off' [-Werror=unused-variable]
 2194 |   static const int db_len_off= 128;
      |                    ^~~~~~~~~~
/plugin/server_audit/server_audit.c:2193:20: error: unused variable 'db_off' [-Werror=unused-variable]
 2193 |   static const int db_off= 120;
      |                    ^~~~~~
/plugin/server_audit/server_audit.c:2192:20: error: unused variable 'cmd_off' [-Werror=unused-variable]
 2192 |   static const int cmd_off= 4432;
      |                    ^~~~~~~
At top level:
/plugin/server_audit/server_audit.c:2192:20: error: 'cmd_off' defined but not used [-Werror=unused-const-variable=]
/plugin/server_audit/server_audit.c:2193:20: error: 'db_off' defined but not used [-Werror=unused-const-variable=]
 2193 |   static const int db_off= 120;
      |                    ^~~~~~
/plugin/server_audit/server_audit.c:2194:20: error: 'db_len_off' defined but not used [-Werror=unused-const-variable=]
 2194 |   static const int db_len_off= 128;
      |                    ^~~~~~~~~~
cc1: all warnings being treated as errors

tested on:
$ uname -a
SunOS openindiana 5.11 illumos-b97b1727bc i86pc i386 i86pc

3 files changed, 10 insertions, 7 deletions

diff --git a/include/my_alarm.h b/include/my_alarm.h
index 6010da6e2c3..bc0004476ca 100644
--- a/include/my_alarm.h
+++ b/include/my_alarm.h
@@ -29,6 +29,13 @@ extern ulong my_time_to_wait_for_lock;
 
 #if defined(HAVE_ALARM) && !defined(NO_ALARM_LOOP)
 #include <signal.h>
+#ifdef HAVE_SIGHANDLER_T
+#define sig_return sighandler_t
+#elif defined(SOLARIS) || defined(__sun) || defined(__APPLE__)
+typedef void (*sig_return)(int); /* Returns type from signal */
+#else
+typedef void (*sig_return)(void); /* Returns type from signal */
+#endif
 #define ALARM_VARIABLES uint alarm_old=0; \
 			sig_return alarm_signal=0
 #define ALARM_INIT	my_have_got_alarm=0 ; \
diff --git a/include/my_global.h b/include/my_global.h
index 8103f82a7e2..5e96400eac1 100644
--- a/include/my_global.h
+++ b/include/my_global.h
@@ -531,13 +531,6 @@ typedef int	my_socket;	/* File descriptor for sockets */
 #endif
 /* Type for fuctions that handles signals */
 #define sig_handler RETSIGTYPE
-C_MODE_START
-#ifdef HAVE_SIGHANDLER_T
-#define sig_return sighandler_t
-#else
-typedef void (*sig_return)(void); /* Returns type from signal */
-#endif
-C_MODE_END
 #if defined(__GNUC__) && !defined(_lint)
 typedef char	pchar;		/* Mixed prototypes can take char */
 typedef char	puchar;		/* Mixed prototypes can take char */
diff --git a/include/violite.h b/include/violite.h
index 45273ac5f24..b9ab7aeb99a 100644
--- a/include/violite.h
+++ b/include/violite.h
@@ -138,6 +138,9 @@ typedef my_socket YASSL_SOCKET_T;
 #define YASSL_SOCKET_T_DEFINED
 #include <openssl/ssl.h>
 #include <openssl/err.h>
+#ifdef DEPRECATED
+#undef DEPRECATED
+#endif
 
 enum enum_ssl_init_error
 {