fix: ubiquitous constant defined in header

..resulting in that global constant being allocated a gazillion times

src/lib/symbol-impl.cpp

@@ -50,6 +50,9 @@ using boost::hash_combine;
 
 namespace lib {
   
+  const size_t STRING_MAX_RELEVANT = 1000;
+  
+  
   /** equality on Symbol values is defined
    *  based on the content, not the address. */
   bool

src/lib/symbol.hpp

@@ -112,7 +112,7 @@ namespace lib {
   /** safety guard: maximum number of chars to process.
    *  For comparisons, hash calculations etc., when dealing
    *  with raw char ptrs (typically literal values) */
-  const size_t STRING_MAX_RELEVANT = 1000;
+  extern const size_t STRING_MAX_RELEVANT;
   
   
   /* ===== to be picked up by ADL ===== */