detect: fix fileext and filename negated match

fix bug in fileext and filename preventing negated match to work
correctly. Previously, negated fileext (such as !"php") would cause a
match anyway on files that have extension php, as the last if would not
be accessed.

Using the same workflow as detect-filemagic we remove the final
isolated if and set it as a branch of the previous if.

src/detect-fileext.c

@@ -116,9 +116,7 @@ static int DetectFileextMatch (ThreadVars *t, DetectEngineThreadCtx *det_ctx,
             ret = 1;
             SCLogDebug("File ext found");
         }
-    }
-
-    if (ret == 0 && (fileext->flags & DETECT_CONTENT_NEGATED)) {
+    } else if (fileext->flags & DETECT_CONTENT_NEGATED) {
         SCLogDebug("negated match");
         ret = 1;
     }

src/detect-filename.c

@@ -156,7 +156,7 @@ static int DetectFilenameMatch (ThreadVars *t, DetectEngineThreadCtx *det_ctx,
         }
     }
 
-    if (ret == 0 && (filename->flags & DETECT_CONTENT_NEGATED)) {
+    else if (filename->flags & DETECT_CONTENT_NEGATED) {
         SCLogDebug("negated match");
         ret = 1;
     }