minor plugin api fixes:

remove #define __attribute__(A) from plugin.h
increase API version because placeholders were added
more robust definition of min_plugin_interface_version


include/mysql/plugin.h:
  move #define __attribute__(A) out of plugin.h (not part of the API)
  increase API version because placeholders were added
plugin/fulltext/plugin_example.c:
  compilation failure on non-GCC compilers
sql/sql_plugin.cc:
  more robust definition of min_plugin_interface_version
  it should work even when we forget to update it

include/mysql/plugin.h

@@ -21,7 +21,7 @@
   Plugin API. Common for all plugin types.
 */
 
-#define MYSQL_PLUGIN_INTERFACE_VERSION 0x0001
+#define MYSQL_PLUGIN_INTERFACE_VERSION 0x0002
 
 /*
   The allowable types of plugins
@@ -31,10 +31,6 @@
 #define MYSQL_FTPARSER_PLUGIN        2  /* Full-text parser plugin      */
 #define MYSQL_MAX_PLUGIN_TYPE_NUM    3  /* The number of plugin types   */
 
-#if !defined(__attribute__) && (defined(__cplusplus) || !defined(__GNUC__)  || __GNUC__ == 2 && __GNUC_MINOR__ < 8)
-#define __attribute__(A)
-#endif
-
 /*
   Macros for beginning and ending plugin declarations.  Between
   mysql_declare_plugin and mysql_declare_plugin_end there should

plugin/fulltext/plugin_example.c

@@ -17,6 +17,10 @@
 #include <ctype.h>
 #include <mysql/plugin.h>
 
+#if !defined(__attribute__) && (defined(__cplusplus) || !defined(__GNUC__)  || __GNUC__ == 2 && __GNUC_MINOR__ < 8)
+#define __attribute__(A)
+#endif
+
 static long number_of_calls= 0; /* for SHOW STATUS, see below */
 
 /*

sql/sql_plugin.cc

@@ -40,7 +40,7 @@ static const char *plugin_interface_version_sym=
 static const char *sizeof_st_plugin_sym=
                    "_mysql_sizeof_struct_st_plugin_";
 static const char *plugin_declarations_sym= "_mysql_plugin_declarations_";
-static int min_plugin_interface_version= 0x0000;
+static int min_plugin_interface_version= MYSQL_PLUGIN_INTERFACE_VERSION & ~0xFF;
 /* Note that 'int version' must be the first field of every plugin
    sub-structure (plugin->info).
 */