git: db9fd99ba8bd - stable/13 - cross-build: Provide mempcpy when building on macOS

The branch stable/13 has been updated by jrtc27:

URL: https://cgit.FreeBSD.org/src/commit/?id=db9fd99ba8bd638f64079d8f0f8a2b282c71a4df

commit db9fd99ba8bd638f64079d8f0f8a2b282c71a4df
Author:     Jessica Clarke <jrtc27@FreeBSD.org>
AuthorDate: 2026-03-23 16:56:09 +0000
Commit:     Jessica Clarke <jrtc27@FreeBSD.org>
CommitDate: 2026-04-02 10:02:04 +0000

    cross-build: Provide mempcpy when building on macOS
    
    We could patch the tzcode config to not use it, but it's simple to
    provide an implementation of it and avoid spreading cross-build
    bootstrapping special cases.
    
    Fixes:          ff2c98b30b57 ("tzcode: Update to 2026a")
    MFC after:      1 week
    
    (cherry picked from commit 47402c9422ec6c9ba76d96414f5a08bd35a9e1fd)
---
 tools/build/Makefile                         | 7 +++++++
 tools/build/cross-build/include/mac/string.h | 2 ++
 2 files changed, 9 insertions(+)

diff --git a/tools/build/Makefile b/tools/build/Makefile
index b6925688896d..92c80493139e 100644
--- a/tools/build/Makefile
+++ b/tools/build/Makefile
@@ -183,6 +183,13 @@ SRCS+=	progname.c
 # Stub implementations of fflagstostr/strtofflags
 SRCS+=	fflags.c
 .endif
+
+.if ${.MAKE.OS} == "Darwin"
+# macOS currently lacks mempcpy
+.PATH: ${LIBC_SRCTOP}/string
+SRCS+=	mempcpy.c
+.endif # ${MAKE.OS} == "Darwin"
+
 # Provide the same arc4random implementation on Linux/macOS
 CFLAGS.arc4random.c+=	-I${SRCTOP}/sys/crypto/chacha20 -D__isthreaded=1
 SRCS+=	arc4random.c arc4random_uniform.c
diff --git a/tools/build/cross-build/include/mac/string.h b/tools/build/cross-build/include/mac/string.h
index 58464f1f9834..8a36bb1f392d 100644
--- a/tools/build/cross-build/include/mac/string.h
+++ b/tools/build/cross-build/include/mac/string.h
@@ -37,6 +37,8 @@
 
 #include_next <string.h>
 
+void	*(mempcpy)(void * __restrict, const void * __restrict, size_t);
+
 /*
  * strchrnul is provided by macOS 15.4 and later.  However, there is
  * no good way to detect the current host version at compile time, so