More win64 warning fixes.

tools/win_dbghelp.cpp

Index: tools/win_dbghelp.cpp
diff --git a/tools/win_dbghelp.cpp b/tools/win_dbghelp.cpp
index ebdbaefcfa2c92f6271f4afeece63f7328fd3d69..57389b430d508f02559c479b37ac7f746df4225e 100644
--- a/tools/win_dbghelp.cpp
+++ b/tools/win_dbghelp.cpp
@@ -209,14 +209,14 @@ void setUpDebuggingFromArgs(const char* vargs0) {
         i -= 4;
     }
 
-    int pos_period = i;
+    size_t pos_period = i;
 
     // Find last \ in path - this is Windows!
     while (i >= 0 && vargs0[i] != '\\') {
         i--;
     }
 
-    int pos_last_slash = i;
+    size_t pos_last_slash = i;
 
     char app_name[MAX_PATH];
     strncpy(app_name, vargs0 + pos_last_slash + 1, pos_period - pos_last_slash - 1);