Prevent -Wshadow warnings with gcc versions 4.8.5, 5.3.1 and 6.2.1.

Zcash: partial (ignoring src/test/script_tests.cpp due to merge conflicts)

src/streams.h

@@ -295,8 +295,8 @@ public:
         return (*this);
     }
 
-    void GetAndClear(CSerializeData &data) {
-        data.insert(data.end(), begin(), end());
+    void GetAndClear(CSerializeData &d) {
+        d.insert(d.end(), begin(), end());
         clear();
     }
 };

src/torcontrol.cpp

@@ -657,26 +657,26 @@ void TorController::reconnect_cb(evutil_socket_t fd, short what, void *arg)
 }
 
 /****** Thread ********/
-struct event_base *base;
+struct event_base *gBase;
 boost::thread torControlThread;
 
 static void TorControlThread()
 {
-    TorController ctrl(base, GetArg("-torcontrol", DEFAULT_TOR_CONTROL));
+    TorController ctrl(gBase, GetArg("-torcontrol", DEFAULT_TOR_CONTROL));
 
-    event_base_dispatch(base);
+    event_base_dispatch(gBase);
 }
 
 void StartTorControl(boost::thread_group& threadGroup, CScheduler& scheduler)
 {
-    assert(!base);
+    assert(!gBase);
 #ifdef WIN32
     evthread_use_windows_threads();
 #else
     evthread_use_pthreads();
 #endif
-    base = event_base_new();
-    if (!base) {
+    gBase = event_base_new();
+    if (!gBase) {
         LogPrintf("tor: Unable to create event_base\n");
         return;
     }
@@ -686,18 +686,18 @@ void StartTorControl(boost::thread_group& threadGroup, CScheduler& scheduler)
 
 void InterruptTorControl()
 {
-    if (base) {
+    if (gBase) {
         LogPrintf("tor: Thread interrupt\n");
-        event_base_loopbreak(base);
+        event_base_loopbreak(gBase);
     }
 }
 
 void StopTorControl()
 {
-    if (base) {
+    if (gBase) {
         torControlThread.join();
-        event_base_free(base);
-        base = 0;
+        event_base_free(gBase);
+        gBase = 0;
     }
 }