date: build failure of cygwin target

[oech3]

- name: "`make install MULTICALL=y` (x86_64-pc-cygwin)"
  shell: 'C:\msys64\usr\bin\bash.exe --login -eo pipefail {0}'
  env:
    CHERE_INVOKING: 1
  run: |
    set -x
    pacman -Sy --noconfirm --needed make rust base-devel
    cargo check -p uu_date

    Checking uu_date v0.8.0 (/d/a/coreutils/coreutils/src/uu/date)
error[E0425]: cannot find value `D_T_FMT` in crate `libc`
  --> src/uu/date/src/locale.rs:33:43
   |
33 |     const DATE_FMT: libc::nl_item = libc::D_T_FMT;
   |                                           ^^^^^^^ not found in `libc`
error[E0425]: cannot find function `nl_langinfo` in crate `libc`
  --> src/uu/date/src/locale.rs:78:37
   |
78 |             let d_t_fmt_ptr = libc::nl_langinfo(DATE_FMT);
   |                                     ^^^^^^^^^^^ not found in `libc`

libc v0.2.186
@tgross35

[oech3]

coreutils/src/uu/date/src/locale.rs

Lines 28 to 33 in 873a7c7

	/// glibc's `_DATE_FMT` has been stable for the last 12 years
	/// being added upstream to libc TODO: update to libc
	#[cfg(target_os = "linux")]
	const DATE_FMT: libc::nl_item = 0x2006c;
	#[cfg(not(target_os = "linux"))]
	const DATE_FMT: libc::nl_item = libc::D_T_FMT;