Fix adb.

9460de1ce80a41cd6171a7e03d9fa7aef2db9dce had a backwards test that means
all adb commands abort. Fix the sense of the test.

Bug: http://b/30445394
Change-Id: I4b8ee697f7d305b57f9cd1a70ae919869dee994d
diff --git a/adb_client.cpp b/adb_client.cpp
index 0b2fc1e..919e1c1 100644
--- a/adb_client.cpp
+++ b/adb_client.cpp
@@ -60,8 +60,8 @@
 }
 
 void adb_set_socket_spec(const char* socket_spec) {
-    if (!__adb_server_socket_spec) {
-        LOG(FATAL) << "attempted to reinitialize adb_server_socket_spec";
+    if (__adb_server_socket_spec) {
+        LOG(FATAL) << "attempted to reinitialize adb_server_socket_spec " << socket_spec << " (was " << __adb_server_socket_spec << ")";
     }
     __adb_server_socket_spec = socket_spec;
 }