package/erofs-utils: add patch to resolve PAGE_SIZE redefinition

This patch resolves PAGE_SIZE redefinition reported by autobuilders,
with toolchains using musl, on x86 (32- or 64-bit) platforms.

Fixes:
  - http://autobuild.buildroot.net/results/340b98caa45bafd43f109002be9da59ba7f6d971
  - http://autobuild.buildroot.net/results/42cd24535ab38cb9b416b730a034a1dbe3293bf5
  - http://autobuild.buildroot.net/results/260cdb3203e9141e674f38a2acd127d10320f8fa

Signed-off-by: Gao Xiang <hsiangkao@aol.com>
[yann.morin.1998@free.fr:
  - update commit log with details about conditions
  - add two autobuilder references
]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/erofs-utils/0004-erofs-utils-avoid-PAGE_SIZE-redefinition.patch

@@ -0,0 +1,57 @@
+From 6c087a91c968197b5a95578fc645617947c943ad Mon Sep 17 00:00:00 2001
+From: Gao Xiang <hsiangkao@aol.com>
+Date: Wed, 25 Mar 2020 15:42:22 +0800
+Subject: [PATCH] erofs-utils: avoid PAGE_SIZE redefinition
+
+Buildroot autobuild reported a PAGE_SIZE redefinition with some
+configrations on i586 toolchain [1] (I didn't notice such report
+from erofs-utils travis CI or distribution builds before.)
+
+In file included from config.c:11:
+../include/erofs/internal.h:27: error: "PAGE_SIZE" redefined [-Werror]
+ #define PAGE_SIZE  (1U << PAGE_SHIFT)
+
+In file included from ../include/erofs/defs.h:17,
+                 from ../include/erofs/config.h:12,
+                 from ../include/erofs/print.h:12,
+                 from config.c:10:
+.../sysroot/usr/include/limits.h:89: note: this is the location of the previous definition
+ #define PAGE_SIZE PAGESIZE
+
+cc1: all warnings being treated as errors
+
+Fix it now.
+
+[1] http://autobuild.buildroot.net/results/340b98caa45bafd43f109002be9da59ba7f6d971
+Link: https://lore.kernel.org/r/20200325082930.2025-1-hsiangkao@aol.com
+Signed-off-by: Gao Xiang <hsiangkao@aol.com>
+---
+ include/erofs/internal.h | 10 ++++++++++
+ 1 file changed, 10 insertions(+)
+
+diff --git a/include/erofs/internal.h b/include/erofs/internal.h
+index e7d5a64..41da189 100644
+--- a/include/erofs/internal.h
++++ b/include/erofs/internal.h
+@@ -23,8 +23,18 @@ typedef unsigned short umode_t;
+ #define PATH_MAX        4096    /* # chars in a path name including nul */
+ #endif
+ 
++#ifndef PAGE_SHIFT
+ #define PAGE_SHIFT		(12)
++#endif
++
++#ifndef PAGE_SIZE
+ #define PAGE_SIZE		(1U << PAGE_SHIFT)
++#endif
++
++/* no obvious reason to support explicit PAGE_SIZE != 4096 for now */
++#if PAGE_SIZE != 4096
++#error incompatible PAGE_SIZE is already defined
++#endif
+ 
+ #define LOG_BLOCK_SIZE          (12)
+ #define EROFS_BLKSIZ            (1U << LOG_BLOCK_SIZE)
+-- 
+2.20.1
+