Add missing initialisation
Add missing initialisation

Fixes:
receive.c:1581:6: warning: variable 'rh' is used uninitialized whenever 'if'
      condition is true [-Wsometimes-uninitialized]
        if (( dff = fdopen( dfile_fd, "w" )) == NULL ) {
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
receive.c:2423:27: note: uninitialized use occurs here
    receive_headers_free( rh );

simta/simta,simta/simta,simta/simta