sys-kernel/linux-headers: add musl patch for 5.10

Stable revbump given this is exactly what's already applied in ::musl
and we're only applying this new patch conditionally. We want installs
done with the new stages to not have to "downgrade" to the ::gentoo
version which lacks the header fixes that this patch _now_ adds.

Signed-off-by: Sam James <[email protected]>

sys-kernel/linux-headers/files/linux-headers-5.10-Use-stddefs.h-instead-of-compiler.h.patch

@@ -0,0 +1,27 @@
+Needed for musl.
+
+From 9eb3c31415686ae1296d7d450f886eeba5861ec1 Mon Sep 17 00:00:00 2001
+From: Jory Pratt <[email protected]>
+Date: Thu, 3 Jun 2021 18:41:28 -0500
+Subject: [PATCH] Use stddefs.h instead of compiler.h
+
+---
+ include/uapi/linux/swab.h | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/include/uapi/linux/swab.h b/include/uapi/linux/swab.h
+index 7272f85..3736f2f 100644
+--- a/include/uapi/linux/swab.h
++++ b/include/uapi/linux/swab.h
+@@ -3,7 +3,7 @@
+ #define _UAPI_LINUX_SWAB_H
+
+ #include <linux/types.h>
+-#include <linux/compiler.h>
++#include <linux/stddef.h>
+ #include <asm/bitsperlong.h>
+ #include <asm/swab.h>
+
+-- 
+2.31.1
+

sys-kernel/linux-headers/linux-headers-5.10-r1.ebuild

@@ -0,0 +1,50 @@
+# Copyright 1999-2021 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI="6"
+
+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}-${PATCH_VER}.tar.xz}
+"
+
+KEYWORDS="~alpha amd64 arm arm64 hppa ~ia64 ~m68k ~mips ppc ppc64 ~riscv ~s390 sparc x86 ~amd64-linux ~x86-linux"
+
+DEPEND="app-arch/xz-utils
+	dev-lang/perl"
+RDEPEND=""
+
+S=${WORKDIR}/linux-${PV}
+
+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
+	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
+}