broken dead code in pg_lzcompress.h

I came across the following obviously corrupt macro in pg_lzcompress.h:

#define PGLZ_IS_COMPRESSED(_lzdata)        ((_lzdata)->varsize !=                \
e                                         (_lzdata)->rawsize +            e    \
           sizeof(PGLZ_Header))
 
The reason we have not noticed its brokenness is that it's only used in
macro pglz_decomp_init, which is used nowhere.  In fact there seems to
be quite a lot of dead code in this header.  I'm inclined to remove
everything that's not referenced, rather than try to fix it.
        regards, tom lane