Close file descriptor after dup2

Close the file descriptor assgined by open if it
is not the same as the newfd.

Fixes coverity 1028694

(It seems likely that coverity will not agree that it is
fixed, since it will not recognize the belt and suspenders
checking of the fd being the value dup'ed to).

mythtv/libs/libmythbase/mythsystemunix.cpp

@@ -920,6 +920,15 @@ void MythSystemLegacyUnix::Fork(time_t timeout)
                             "\n\t\t\tfailed to duplicate file descriptor: " 
                          << strerror(errno) << endl;
                 }
+                if (fd != 0)    // if fd was zero, do not close
+                {
+                    if (close(fd) < 0)
+                    {
+                        cerr << locerr
+                             << "Unable to close stdin redirect /dev/null: "
+                             << strerror(errno) << endl;
+                    }
+                }
             }
             else
             {
@@ -955,6 +964,15 @@ void MythSystemLegacyUnix::Fork(time_t timeout)
                             "\n\t\t\tfailed to duplicate file descriptor: " 
                          << strerror(errno) << endl;
                 }
+                if (fd != 1)    // if fd was one, do not close
+                {
+                   if (close(fd) < 0)
+                   {
+                       cerr << locerr
+                            << "Unable to close stdout redirect /dev/null: "
+                            << strerror(errno) << endl;
+                   }
+                }
             }
             else
             {
@@ -990,6 +1008,15 @@ void MythSystemLegacyUnix::Fork(time_t timeout)
                             "\n\t\t\tfailed to duplicate file descriptor: " 
                          << strerror(errno) << endl;
                 }
+                if (fd != 2)    // if fd was two, do not close
+                {
+                   if (close(fd) < 0)
+                   {
+                       cerr << locerr
+                            << "Unable to close stderr redirect /dev/null: "
+                            << strerror(errno) << endl;
+                   }
+                }
             }
             else
             {