[build] fix static var issue

src/line_buffer.cc

@@ -67,6 +67,10 @@ static const ssize_t DEFAULT_INCREMENT = 128 * 1024;
 static const ssize_t INITIAL_COMPRESSED_BUFFER_SIZE = 5 * 1024 * 1024;
 static const ssize_t MAX_COMPRESSED_BUFFER_SIZE = 32 * 1024 * 1024;
 
+const ssize_t line_buffer::DEFAULT_LINE_BUFFER_SIZE = 256 * 1024;
+const ssize_t line_buffer::MAX_LINE_BUFFER_SIZE
+    = 4 * 4 * line_buffer::DEFAULT_LINE_BUFFER_SIZE;
+
 class io_looper : public isc::service<io_looper> {};
 
 struct io_looper_tag {};

src/line_buffer.hh

@@ -67,9 +67,8 @@ struct line_info {
  */
 class line_buffer {
 public:
-    static const ssize_t DEFAULT_LINE_BUFFER_SIZE = 256 * 1024;
-    static const ssize_t MAX_LINE_BUFFER_SIZE
-        = 4 * 4 * DEFAULT_LINE_BUFFER_SIZE;
+    static const ssize_t DEFAULT_LINE_BUFFER_SIZE;
+    static const ssize_t MAX_LINE_BUFFER_SIZE;
     class error : public std::exception {
     public:
         error(int err) : e_err(err){};