moved exception definition to header file.

lib/mt/CThreadRep.cpp

@@ -24,9 +24,6 @@
 
 #endif
 
-// FIXME -- temporary exception type
-class XThreadUnavailable { };
-
 //
 // CThreadRep
 //

lib/mt/XThread.h

@@ -27,6 +27,12 @@ must rethrow it if caught (by XThreadCancel, XThread, or ...).
 */
 class XThreadCancel : public XThread { };
 
+//! Thread creation exception
+/*!
+Thrown when a thread cannot be created.
+*/
+class XThreadUnavailable { };
+
 /*!
 \def RETHROW_XTHREAD
 Convenience macro to rethrow an XThread exception but ignore other