gcc warning fixes.

This patch fixes gcc warning:
    warning: suggest braces around empty body in an ‘if’ statement
This was the case in  when the macro SCLogDebug was used:
    if (ssn != NULL)
        SCLogDebug("ssn->alproto %"PRIu16"", ssn->alproto);

It also fixes a signed-unsigned comparison.

src/detect-window.c

@@ -149,11 +149,6 @@ DetectWindowData *DetectWindowParse(char *windowstr) {
             if (-1 == ByteExtractStringUint16(&wd->size, 10, 0, str_ptr)) {
                 goto error;
             }
-
-            /* If greater than 1GB window */
-            if (wd->size < MIN_WINDOW_VALUE || wd->size > MAX_WINDOW_VALUE) {
-                goto error;
-            }
         }
     }
 

src/util-debug.h

@@ -285,7 +285,7 @@ extern int sc_log_module_cleaned;
 /* Avoid the overhead of using the debugging subsystem, in production mode */
 #ifndef DEBUG
 
-#define SCLogDebug(...)
+#define SCLogDebug(...)                 do { } while (0)
 
 #define SCEnter(...)