toolchain/59848: Cross-building of src/ fails.

[jkoshy%netbsd.org@localhost]

>Number:         59848
>Category:       toolchain
>Synopsis:       Cross-building of src/ fails.
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Dec 19 13:25:00 +0000 2025
>Originator:     Joseph Koshy
>Release:        NetBSD 10.99.4
>Organization:
	NetBSD Project
>Environment:
>Description:
	Cross-building of src/ fails.

	% uname -o
	GNU/Linux
	% ./build.sh -j1 -U -u -T ~/tools/amd64 -O ~/obj/amd64 -m amd64  distribution
	[...]
	dependall ===> tools/compat
	#   compile  compat/mempcpy.lo
	cc -O   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -I. -I./include -I/disk/NetBSD/src-etc/tools/compat -I/disk/NetBSD/src-etc/tools/compat/sys  -DHAVE_NBTOOL_CONFIG_H=1 -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -I. -I./include -I/disk/NetBSD/src-etc/tools/compat -I/disk/NetBSD/src-etc/tools/compat/sys -DHAVE_NBTOOL_CONFIG_H=1 -D_FILE_OFFSET_BITS=64 -D__DBINTERFACE_PRIVATE -c -o mempcpy.lo.o    /disk/NetBSD/src-etc/tools/compat/../../lib/libc/string/mempcpy.c
	/disk/NetBSD/src-etc/tools/compat/../../lib/libc/string/mempcpy.c:29:9: error: expected declaration specifiers or '...' before string constant
	   29 | __RCSID("$NetBSD: mempcpy.c,v 1.2 2025/12/18 00:18:55 christos Exp $");
	      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	*** Failed target: mempcpy.lo
	*** In directory: /disk/NetBSD/src-etc/tools/compat
	*** Failed commands:
		${_MKTARGET_COMPILE}
		=> @echo '#  ' "compile " compat/mempcpy.lo
		${HOST_COMPILE.c} -o ${.TARGET}.o ${COPTS.${.IMPSRC:T}} ${CPUFLAGS.${.IMPSRC:T}} ${CPPFLAGS.${.IMPSRC:T}} ${.IMPSRC}
		=> cc -O   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -I. -I./include -I/disk/NetBSD/src-etc/tools/compat -I/disk/NetBSD/src-etc/tools/compat/sys  -DHAVE_NBTOOL_CONFIG_H=1 -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -I. -I./include -I/disk/NetBSD/src-etc/tools/compat -I/disk/NetBSD/src-etc/tools/compat/sys -DHAVE_NBTOOL_CONFIG_H=1 -D_FILE_OFFSET_BITS=64 -D__DBINTERFACE_PRIVATE -c -o mempcpy.lo.o    /disk/NetBSD/src-etc/tools/compat/../../lib/libc/string/mempcpy.c
		${MV} ${.TARGET}.o ${.TARGET}
		=> mv -f mempcpy.lo.o mempcpy.lo
	*** [mempcpy.lo] Error code 1
>Fix: