style: remove trailing whitespace

Result of running 'hg m5style --skip-all --fix-white -a'.
diff --git a/src/base/inet.hh b/src/base/inet.hh
index d7e0039..7d1235c 100644
--- a/src/base/inet.hh
+++ b/src/base/inet.hh
@@ -521,7 +521,7 @@
 
     void sum(uint16_t sum) { th_sum = sum; }
     void seq(uint32_t _seq) { th_seq = htonl(_seq); }
-    void flags(uint8_t _flags) { th_flags  = _flags; } 
+    void flags(uint8_t _flags) { th_flags  = _flags; }
 
     bool options(std::vector<const TcpOpt *> &vec) const;