Remove attribute_hidden for wchar ifunc symbols.

On s390 (31bit) various debug/tst-*chk* testcases are failing as the tests
are ending with a segmentation fault.

One test is e.g. calling wcsnrtombs in debug/tst-chk1.c:1549.
The function wcsnrtombs itself calls __wcsnlen. This function is called via
PLT! The PLT-stub itself loads the address from GOT (r12 is assumed to be
the GOT-pointer). In this case the loaded address is zero and the following
branch leads to the segmentation fault.

Due to the attribute_hidden in commit 44af8a32c341672b5160fdc2839767e9a837ad26
"Mark internal wchar functions with attribute_hidden [BZ #18822]"
for e.g. the __wcsnlen function, r12 is not loaded with the GOT-pointer
in wcsnrtombs.

On s390x (64bit), this __wcsnlen call is also using the PLT-stub. But it is
not failing as the GOT-pointer is setup with larl-instruction by the PLT-stub
itself.
Note: On s390x/s390, __wcsnlen is an IFUNC symbol.

On x86_64, __wcsnlen is also an IFUNC symbol and is called via PLT, too.

Further IFUNC symbols on s390 which were marked as hidden by the mentioned
commit are: __wcscat, __wcsncpy, __wcpncpy, __wcschrnul.

This patch removes the attribute_hidden in wchar.h.
Then the compiler setups e.g. r12 on s390 in order to call __wcsnlen via PLT.

ChangeLog:

	* include/wchar.h (__wcsnlen, __wcscat, __wcsncpy, __wcpncpy,
	__wcschrnul): Remove attribute_hidden.

2 files changed, 10 insertions, 7 deletions

diff --git a/ChangeLog b/ChangeLog
index 50da3df0b9..ca6024c35c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2017-11-21  Stefan Liebler  <stli@linux.vnet.ibm.com>
+
+	* include/wchar.h (__wcsnlen, __wcscat, __wcsncpy, __wcpncpy,
+	__wcschrnul): Remove attribute_hidden.
+
 2017-11-20  Paul Eggert  <eggert@cs.ucla.edu>
 
 	regex: don't assume uint64_t or uint32_t
diff --git a/include/wchar.h b/include/wchar.h
index 24b2eaa5f9..1db0ac8278 100644
--- a/include/wchar.h
+++ b/include/wchar.h
@@ -152,9 +152,8 @@ extern int __wcsncasecmp (const wchar_t *__s1, const wchar_t *__s2,
      __attribute_pure__;
 extern size_t __wcslen (const wchar_t *__s) __attribute_pure__;
 extern size_t __wcsnlen (const wchar_t *__s, size_t __maxlen)
-     attribute_hidden __attribute_pure__;
-extern wchar_t *__wcscat (wchar_t *dest, const wchar_t *src)
-     attribute_hidden;
+     __attribute_pure__;
+extern wchar_t *__wcscat (wchar_t *dest, const wchar_t *src);
 extern wint_t __btowc (int __c) attribute_hidden;
 extern int __mbsinit (const __mbstate_t *__ps);
 extern size_t __mbrtowc (wchar_t *__restrict __pwc,
@@ -182,11 +181,10 @@ extern size_t __wcsnrtombs (char *__restrict __dst,
 			    __mbstate_t *__restrict __ps)
      attribute_hidden;
 extern wchar_t *__wcsncpy (wchar_t *__restrict __dest,
-			   const wchar_t *__restrict __src, size_t __n)
-     attribute_hidden;
+			   const wchar_t *__restrict __src, size_t __n);
 extern wchar_t *__wcpcpy (wchar_t *__dest, const wchar_t *__src);
 extern wchar_t *__wcpncpy (wchar_t *__dest, const wchar_t *__src,
-			   size_t __n) attribute_hidden;
+			   size_t __n);
 extern wchar_t *__wmemcpy (wchar_t *__s1, const wchar_t *s2,
 			   size_t __n) attribute_hidden;
 extern wchar_t *__wmempcpy (wchar_t *__restrict __s1,
@@ -195,7 +193,7 @@ extern wchar_t *__wmempcpy (wchar_t *__restrict __s1,
 extern wchar_t *__wmemmove (wchar_t *__s1, const wchar_t *__s2,
 			    size_t __n) attribute_hidden;
 extern wchar_t *__wcschrnul (const wchar_t *__s, wchar_t __wc)
-     attribute_hidden __attribute_pure__;
+     __attribute_pure__;
 
 extern wchar_t *__wmemset_chk (wchar_t *__s, wchar_t __c, size_t __n,
 			       size_t __ns) __THROW;