sys-kernel/linux-headers: fix 5.10 for musl (sysinfo.h)

Notably fixes btrfs-progs build.

Closes: https://bugs.gentoo.org/828726
Signed-off-by: Sam James <sam@gentoo.org>

sys-kernel/linux-headers/files/linux-headers-5.10-remove-inclusion-sysinfo.h.patch

@@ -0,0 +1,24 @@
+https://git.alpinelinux.org/aports/tree/main/linux-headers/0003-remove-inclusion-of-sysinfo.h-in-kernel.h.patch
+https://bugs.gentoo.org/828726
+
+From: rofl0r <retnyg@gmx.net>
+Date: Mon, 20 Jan 2014 21:31:34 +0100
+Subject: [PATCH 3/3] remove inclusion of sysinfo.h in kernel.h
+
+the declaration of struct sysinfo clashes with userspace.
+it's not quite clear why that header was included from kernel.h,
+as none of its functionality is needed.
+--- a/include/uapi/linux/kernel.h
++++ b/include/uapi/linux/kernel.h
+@@ -2,7 +2,9 @@
+ #ifndef _UAPI_LINUX_KERNEL_H
+ #define _UAPI_LINUX_KERNEL_H
+ 
++#ifdef __GLIBC__
+ #include <linux/sysinfo.h>
++#endif
+ #include <linux/const.h>
+ 
+ #endif /* _UAPI_LINUX_KERNEL_H */
+
+

sys-kernel/linux-headers/linux-headers-5.10-r2.ebuild

@@ -0,0 +1,49 @@
+# Copyright 1999-2021 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=7
+
+ETYPE="headers"
+H_SUPPORTEDARCH="alpha amd64 arc arm arm64 avr32 cris frv hexagon hppa ia64 m68k metag microblaze mips mn10300 nios2 openrisc ppc ppc64 riscv s390 score sh sparc x86 xtensa"
+inherit kernel-2 toolchain-funcs
+detect_version
+
+PATCH_PV=${PV} # to ease testing new versions against not existing patches
+PATCH_VER="1"
+SRC_URI="${KERNEL_URI}
+	${PATCH_VER:+mirror://gentoo/gentoo-headers-${PATCH_PV}-${PATCH_VER}.tar.xz}
+	${PATCH_VER:+https://dev.gentoo.org/~sam/distfiles/gentoo-headers-${PATCH_PV}-${PATCH_VER}.tar.xz}
+"
+S="${WORKDIR}"/linux-${PV}
+
+KEYWORDS="~alpha ~amd64 ~arm ~arm64 ~hppa ~ia64 ~m68k ~mips ~ppc ~ppc64 ~riscv ~s390 ~sparc ~x86 ~amd64-linux ~x86-linux"
+
+BDEPEND="app-arch/xz-utils
+	dev-lang/perl"
+
+src_unpack() {
+	unpack ${A}
+}
+
+src_prepare() {
+	[[ -n ${PATCH_VER} ]] && eapply "${WORKDIR}"/${PATCH_PV}/*.patch
+
+	if use elibc_musl ; then
+		# TODO: May need forward porting to newer versions
+		eapply "${FILESDIR}"/${PN}-5.10-Use-stddefs.h-instead-of-compiler.h.patch
+		eapply "${FILESDIR}"/${PN}-5.10-remove-inclusion-sysinfo.h.patch
+	fi
+
+	default
+}
+
+src_test() {
+	emake headers_check ${xmakeopts}
+}
+
+src_install() {
+	kernel-2_src_install
+
+	find "${ED}" '(' -name '.install' -o -name '*.cmd' ')' -delete
+	find "${ED}" -depth -type d -delete 2>/dev/null
+}