wrasse, at least, moans about the lack of any "return" statement
in these functions.  You'd think pretty much everything would
know that exit(1) doesn't return, but evidently not.
    return &streamer->base;
 #else
    pg_fatal("this build does not support gzip compression");
+   return NULL;                /* keep compiler quiet */
 #endif
 }
 
    return &streamer->base;
 #else
    pg_fatal("this build does not support gzip compression");
+   return NULL;                /* keep compiler quiet */
 #endif
 }
 
 
    return &streamer->base;
 #else
    pg_fatal("this build does not support lz4 compression");
+   return NULL;                /* keep compiler quiet */
 #endif
 }
 
    return &streamer->base;
 #else
    pg_fatal("this build does not support lz4 compression");
+   return NULL;                /* keep compiler quiet */
 #endif
 }
 
 
    return &streamer->base;
 #else
    pg_fatal("this build does not support zstd compression");
+   return NULL;                /* keep compiler quiet */
 #endif
 }
 
    return &streamer->base;
 #else
    pg_fatal("this build does not support zstd compression");
+   return NULL;                /* keep compiler quiet */
 #endif
 }