git: f147cf0ee2b2 - main - dtc: Ensure it is built in C++17 mode

The branch main has been updated by emaste:

URL: https://cgit.FreeBSD.org/src/commit/?id=f147cf0ee2b2642c0a133a71c8a5dc018518d923

commit f147cf0ee2b2642c0a133a71c8a5dc018518d923
Author:     Jose Luis Duran <jlduran@gmail.com>
AuthorDate: 2023-09-29 13:24:32 +0000
Commit:     Ed Maste <emaste@FreeBSD.org>
CommitDate: 2023-09-29 13:26:51 +0000

    dtc: Ensure it is built in C++17 mode
    
    Explicitly specify the C++ standard to be used in the Makefile.
    This prevents macOS cross-builds from using the default gnu++98 and
    fail.  This syncs dtc with upstream commit
    39a58cfaab7d55c7975ebf905d859ba91a369fa0.
    
    Reviewed by: emaste
    Fixes: 29a55fd09b0a ("dtc: Sync with upstream commit 26a0fe5")
    Differential Revision: https://reviews.freebsd.org/D42006
---
 usr.bin/dtc/Makefile | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/usr.bin/dtc/Makefile b/usr.bin/dtc/Makefile
index d7661ae164c3..9b1aff13511f 100644
--- a/usr.bin/dtc/Makefile
+++ b/usr.bin/dtc/Makefile
@@ -6,6 +6,8 @@ WARNS?=	3
 
 CXXFLAGS+=	-fno-rtti -fno-exceptions
 
+CXXSTD=	c++17
+
 NO_SHARED?=NO
 
 .include <bsd.prog.mk>