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_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