Bug #245176 --> several unsigned integers in the core bayesian algorithm should be signed integers because

they can be negative. Slightly improves our false negative rate on the benchmark.

Patch by Lorenzo Colitti

mailnews/extensions/bayesian-spam-filter/src/nsBayesianFilter.cpp

@@ -989,7 +989,7 @@ void nsBayesianFilter::classifyMessage(Tokenizer& tokenizer, const char* message
     first = (goodclues > 150) ? count - 150 : 0;
 
     double H = 1.0, S = 1.0;
-    PRUint32 Hexp = 0, Sexp = 0;
+    PRInt32 Hexp = 0, Sexp = 0;
     goodclues=0;
     int e;