Add support for several platforms to obtain the real thread ID.

Already had the pthread ID which is not the same.  The most obvious enhancement
is in the "core show threads" output. As stated in the utils header, if the
platform isn't supported -1 is reported (instead of the process ID previously).


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@298137 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/utils.h

@@ -758,4 +758,11 @@ int ast_str_to_eid(struct ast_eid *eid, const char *s);
  */
 int ast_eid_cmp(const struct ast_eid *eid1, const struct ast_eid *eid2);
 
+/*!
+ * \brief Get current thread ID
+ * \param None
+ * \return the ID if platform is supported, else -1
+ */
+int ast_get_tid(void);
+
 #endif /* _ASTERISK_UTILS_H */