MDEV-9618 solaris sparc build fails on 10.1.

Compiler there is strict about the C/C++ call model
        mixing in function variable assumptions.
        Fixed by adding some 'extern "C"' and changing
        '?' operator with 'if'.

include/mysql/plugin_audit.h

@@ -23,6 +23,10 @@
 
 #include "plugin.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #define MYSQL_AUDIT_CLASS_MASK_SIZE 1
 
 #define MYSQL_AUDIT_INTERFACE_VERSION 0x0302
@@ -175,4 +179,8 @@ struct st_mysql_audit
 };
 
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif

include/mysql/plugin_auth.h

@@ -31,6 +31,10 @@
 
 #include <mysql/plugin_auth_common.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* defines for MYSQL_SERVER_AUTH_INFO.password_used */
 
 #define PASSWORD_USED_NO         0
@@ -122,5 +126,10 @@ struct st_mysql_auth
   */
   int (*authenticate_user)(MYSQL_PLUGIN_VIO *vio, MYSQL_SERVER_AUTH_INFO *info);
 };
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif
 

include/mysql/plugin_encryption.h

@@ -27,6 +27,10 @@
 
 #include <mysql/plugin.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #define MariaDB_ENCRYPTION_INTERFACE_VERSION 0x0300
 
 /**
@@ -114,5 +118,9 @@ struct st_mariadb_encryption
   */
   unsigned int (*encrypted_length)(unsigned int slen, unsigned int key_id, unsigned int key_version);
 };
+
+#ifdef __cplusplus
+}
+#endif
 #endif
 

include/mysql/plugin_ftparser.h

@@ -18,6 +18,10 @@
 #define _my_plugin_ftparser_h
 #include "plugin.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /*************************************************************************
   API for Full-text parser plugin. (MYSQL_FTPARSER_PLUGIN)
 */
@@ -208,5 +212,9 @@ struct st_mysql_ftparser
 };
 
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif
 

include/mysql/plugin_password_validation.h

@@ -26,6 +26,10 @@
 
 #include <mysql/plugin.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #define MariaDB_PASSWORD_VALIDATION_INTERFACE_VERSION 0x0100
 
 /**
@@ -41,5 +45,10 @@ struct st_mariadb_password_validation
   int (*validate_password)(MYSQL_LEX_STRING *username,
                            MYSQL_LEX_STRING *password);
 };
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif