Fix gcc warning about inline function being marked as dllimport.

[SVN r24975]

include/boost/thread/exceptions.hpp

@@ -34,7 +34,7 @@ protected:
 public:
     ~thread_exception() throw();
 
-    int native_error() const { return m_sys_err; }
+    int native_error() const;
 
     const char* message() const;
 

src/exceptions.cpp

@@ -82,6 +82,11 @@ thread_exception::~thread_exception() throw()
 {
 }
 
+int thread_exception::native_error() const
+{
+    return m_sys_err; 
+}
+
 const char* thread_exception::message() const
 {
     if (m_sys_err != 0)