Fix build on Cygwin

[stilor]

The -lcygwin -lc actually breaks the build: elf2flt picks up the symbols
for getopt/optarg via <getopt.h> in binutils-X.Y/include, where optarg
is declared without dllimport attribute. Therefore it pulls in getopt()
from libc/libcygwin, but since optarg is not prefixed with imp_, it is
pulled from libiberty. But the object file in libiberty also contains
getopt() thus resulting in multiple definitions thereof.

Signed-off-by: Alexey Neyman stilor@att.net

[stilor]

To clarify: yes, I saw the comments in the deleted code. However, what I am seeing while trying to build elf2flt (via crosstool-ng) on cygwin is exactly the opposite: these workarounds result in libcygwin/libiberty clash for getopt. I am not sure how the original problem was manifested - was it some ancient binutils that didn't have getopt.h, or what?

[vapier]

the full history is in git, so you can simply look at the commit log to see where this code was added -- in commit 4565de8.

deleting this code outright won't work, sorry. you're breaking one system to fix another.

[stilor]

What about adding binutils headers dirs after the system dirs (e.g. with -idirafter)? That would match the order of headers with that of the libraries. I haven't tested that yet, but I think it should be another way of fixing Cygwin build.

Or, those blocks can be specifically made dependent on OS X.

The problem is, I don't have a OS X to test.

[vapier]

getopt is a mess.

the getopt.h include was explicitly added to support mingw. that shouldn't be needed though -- mingw headers provide unistd.h. however, deleting that wouldn't help as mingw will include getopt.h from its unistd.h.

i'm not keen on adding -idirafter as it's not exactly a "standard" flag.

how about we change how we utilize the path from --with-bfd-include-dir. instead of adding an -I flag directly to that path, we create a local dir and copy the few headers we actually care about out of it. then we add a -I flag to that path. it'd avoid any conflicts with the getopt.h header from binutils, and we can keep the symbol conflict logic in place that's in configure.ac now.

[stilor]

Ok, the suggested approach: #7