libz not found during build

[moseley]

A common problem on some systems seems to be that configure detects zlib 
but then on link this error is reported (for example on IRIX):

ld32: ERROR 33: Unresolved text symbol "compress2" -- 1st referenced by
./.libs/libswishindex.al(docprop_write.lo).        Use linker option -v
to see when and which objects, archives and dsos are loaded.
ld32: INFO 152: Output file removed because of error.

compress2 is in zlib.

I'm using this in configure:

if test "$with_zlib" = "no"; then
    echo "Disabling compression support"
else
    AC_CHECK_HEADERS(zlib.h,
        AC_CHECK_LIB(z, gzread,[
            AC_DEFINE(HAVE_ZLIB,[],[Do we have zlib])
            if test "x${Z_DIR}" != "x"; then
                Z_CFLAGS="-I${Z_DIR}/include"
                Z_LIBS="-L${Z_DIR}/lib -lz"
                [case ${host} in
                    *-*-solaris*)
                        Z_LIBS="-L${Z_DIR}/lib -R${Z_DIR}/lib -lz"
                        ;;
                esac]
            else
                Z_LIBS="-lz"
            fi]))
fi

I can see that we added some test for solaris at one point.

This problem seems to come up often and I don't really understand what's 
causing it on some platforms.  Isn't the point of AC_CHECK_LIB to make 
sure I can link with the given library?



-- 
Bill Moseley
address@hidden