strftime: Pass the additional flags from "%EY" to "%Ey" [BZ #24096]

The full representation of the alternative calendar year (%EY)
typically includes an internal use of "%Ey".  As a GNU extension,
apply any flags on "%EY" (e.g. "%_EY", "%-EY") to the internal "%Ey",
allowing users of "%EY" to control how the year is padded.

Reviewed-by: Rafal Luzynski <digitalfreak@lingonborough.com>
Reviewed-by: Zack Weinberg <zackw@panix.com>

ChangeLog:

	[BZ #24096]
	* manual/time.texi (strftime): Document "%EC" and "%EY".
	* time/Makefile (tests): Add tst-strftime2.
	(LOCALES): Add ja_JP.UTF-8, lo_LA.UTF-8, and th_TH.UTF-8.
	* time/strftime_l.c (__strftime_internal): Add argument yr_spec to
	override padding for "%Ey".
	If an optional flag ('_' or '-') is specified to "%EY", interpret the
	"%Ey" in the subformat as if decorated with that flag.
	* time/tst-strftime2.c: New file.

1 files changed, 4 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index aec18367a4..76679f3393 100644
--- a/NEWS
+++ b/NEWS
@@ -60,6 +60,10 @@ Major new features:
   alternative year numbers less than 10).  Zero-padding can be
   overridden with the '_' or '-' flags (which are GNU extensions).
 
+* As a GNU extension, the '_' and '-' flags can now be applied to
+  "%EY" to control how the year number is formatted; they have the
+  same effect that they would on "%Ey".
+
 Deprecated and removed features, and other changes affecting compatibility:
 
 * The glibc.tune tunable namespace has been renamed to glibc.cpu and the