Fix abstract unix socket name

For the abstract unix socket address type, the string in the
'sun_path' field of the 'sockaddr_un' struct, is a not null-terminated
string (see unix(7)).

Fix the lentgh calculation of the 'sun_path' field to not add
the termination null byte.
diff --git a/lib/cpp/Makefile.am b/lib/cpp/Makefile.am
index 3a0c4e6..eab2e21 100755
--- a/lib/cpp/Makefile.am
+++ b/lib/cpp/Makefile.am
@@ -88,6 +88,7 @@
                        src/thrift/transport/TTransportUtils.cpp \
                        src/thrift/transport/TBufferTransports.cpp \
                        src/thrift/transport/TWebSocketServer.cpp \
+                       src/thrift/transport/SocketCommon.cpp \
                        src/thrift/server/TConnectedClient.cpp \
                        src/thrift/server/TServer.cpp \
                        src/thrift/server/TServerFramework.cpp \
@@ -206,7 +207,8 @@
                          src/thrift/transport/TBufferTransports.h \
                          src/thrift/transport/TShortReadTransport.h \
                          src/thrift/transport/TZlibTransport.h \
-                         src/thrift/transport/TWebSocketServer.h
+                         src/thrift/transport/TWebSocketServer.h \
+                         src/thrift/transport/SocketCommon.h
 
 include_serverdir = $(include_thriftdir)/server
 include_server_HEADERS = \