gnu: Remove unused patch 'glibc-memchr-overflow-i686.patch'.

This is a followup to commit 67d527e35e.

* gnu/packages/patches/glibc-memchr-overflow-i686.patch: Delete file.
* gnu/local.mk (dist_patch_DATA): Remove it.

gnu/local.mk

@@ -823,7 +823,6 @@ dist_patch_DATA =						\
   %D%/packages/patches/glibc-hurd-magic-pid.patch		\
   %D%/packages/patches/glibc-ldd-x86_64.patch			\
   %D%/packages/patches/glibc-locales.patch			\
-  %D%/packages/patches/glibc-memchr-overflow-i686.patch		\
   %D%/packages/patches/glibc-o-largefile.patch			\
   %D%/packages/patches/glibc-reinstate-prlimit64-fallback.patch	\
   %D%/packages/patches/glibc-vectorized-strcspn-guards.patch	\

gnu/packages/patches/glibc-memchr-overflow-i686.patch

@@ -1,74 +0,0 @@
-Extracted from glibc upstream git repository.  Changes to the ChangeLog have
-been removed.  This patch is needed to fix spurious segmentation faults on
-i686.
-
-From 3abeeec5f46ff036bd9df60bb096e20314ccd078 Mon Sep 17 00:00:00 2001
-From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
-Date: Tue, 14 Mar 2017 14:16:13 -0300
-Subject: [PATCH] Fix i686 memchr overflow calculation (BZ#21182)
-
-This patch fixes the regression added by 23d2770 for final address
-overflow calculation.  The subtraction of the considered size (16)
-at line 120 is at wrong place, for sizes less than 16 subsequent
-overflow check will not take in consideration an invalid size (since
-the subtraction will be negative).  Also, the lea instruction also
-does not raise the carry flag (CF) that is used in subsequent jbe
-to check for overflow.
-
-The fix is to follow x86_64 logic from 3daef2c where the overflow
-is first check and a sub instruction is issued.  In case of resulting
-negative size, CF will be set by the sub instruction and a NULL
-result will be returned.  The patch also add similar tests reported
-in bug report.
-
-Checked on i686-linux-gnu and x86_64-linux-gnu.
-
-	* string/test-memchr.c (do_test): Add BZ#21182 checks for address
-	near end of a page.
-	* sysdeps/i386/i686/multiarch/memchr-sse2.S (__memchr): Fix
-	overflow calculation.
----
- string/test-memchr.c                      | 6 ++++++
- sysdeps/i386/i686/multiarch/memchr-sse2.S | 2 +-
- 3 files changed, 15 insertions(+), 1 deletion(-)
-
-diff --git a/string/test-memchr.c b/string/test-memchr.c
-index 2403c9242b..669e092e7d 100644
---- a/string/test-memchr.c
-+++ b/string/test-memchr.c
-@@ -210,6 +210,12 @@ test_main (void)
-       do_test (0, i, i + 1, i + 1, 0);
-     }
- 
-+  /* BZ#21182 - wrong overflow calculation for i686 implementation
-+     with address near end of the page.  */
-+  for (i = 2; i < 16; ++i)
-+    /* page_size is in fact getpagesize() * 2.  */
-+    do_test (page_size / 2 - i, i, i, 1, 0x9B);
-+
-   do_random_tests ();
-   return ret;
- }
-diff --git a/sysdeps/i386/i686/multiarch/memchr-sse2.S b/sysdeps/i386/i686/multiarch/memchr-sse2.S
-index 910679cfc0..e41f324a77 100644
---- a/sysdeps/i386/i686/multiarch/memchr-sse2.S
-+++ b/sysdeps/i386/i686/multiarch/memchr-sse2.S
-@@ -117,7 +117,6 @@ L(crosscache):
- 
- # ifndef USE_AS_RAWMEMCHR
- 	jnz	L(match_case2_prolog1)
--	lea	-16(%edx), %edx
-         /* Calculate the last acceptable address and check for possible
-            addition overflow by using satured math:
-            edx = ecx + edx
-@@ -125,6 +124,7 @@ L(crosscache):
- 	add	%ecx, %edx
- 	sbb	%eax, %eax
- 	or	%eax, %edx
-+	sub	$16, %edx
- 	jbe	L(return_null)
- 	lea	16(%edi), %edi
- # else
--- 
-2.12.2
-