Add -DNO_LCHMOD for Linux as well.

Matthias Ferdinand reported on pkgsrc-users:

building archivers/unzip on Linux (Ubuntu 14.04 64bit) succeeds, but
produces the following warning:

    ...
    gcc -o unzip  -Lbzip2 unzip.o crc32.o  crypt.o envargs.o explode.o extract.o fileio.o globals.o inflate.o list.o match.o process.o ttyio.o ubz2err.o u
+nreduce.o unshrink.o zipinfo.o unix.o  -s  -L/opt/pkgsrc/lib -Wl,--enable-new-dtags,-R/opt/pkgsrc/lib -lz
    unix.o: In function `set_symlnk_attribs':
=>  unix.c:(.text+0x1840): warning: lchmod is not implemented and will always fail
    ...

(wiz)