libicudata in non-standard directory linking issues.

[Jonathan Adams]

> i'm not sure if adding a defined(__IBMC__) etc. is the right approach
> but if it doesn't break anything...

they added that line for z/OS ... which, I may be wrong, I believe to
be an IBM system ... looking around wikipedia; I found references to
what defines are set when compiling on z/OS ...

there is code a little further down to set _XOPEN_SOURCE_EXTENDED to 0
on Solaris, but Solaris just checks to see if _XOPEN_SOURCE_EXTENDED
is defined ... I guess I could fix it by changing the following
statement to an undef.

> you should try to update your ICU bug with the new patch as well, to get
> upstream's opinion and hopefully a fixed next ICU version.

I updated the patch before I posted the email ... :)

I'll do a git pull and then re-autogen it.

Jon