Fix iconv link command for Cygwin. Inspired by https://www.cygwin.com/git-cygwin-packages/?p=git/cygwin-packages/libiconv.git;a=blob;f=1.16-cross-install.patch;h=7b3c5c0d761497a20abf0e4cc38d74f2755445fb;hb=HEAD . Rationale: libintl may depends on libiconv. * src/Makefile.in (install): On the link command line, mention libintl before libiconv.