Work around an LTO-related build issue

protobuf-c.spec

@@ -15,7 +15,7 @@
 
 Name:           %{?scl_prefix}protobuf-c
 Version:        1.4.1
-Release:        3%{?dist}
+Release:        4%{?dist}
 Summary:        C bindings for Google's Protocol Buffers
 
 License:        BSD
@@ -65,6 +65,9 @@ This package contains protobuf-c headers and libraries.
 %if 0%{?rhel} && 0%{?rhel} < 8
 scl enable devtoolset-8 -- <<\EOF
 %endif
+# https://github.com/protobuf-c/protobuf-c/issues/483
+%set_build_flags
+export CXXFLAGS="${CXXFLAGS} -std=c++17"
 %configure --disable-static
 %{?scl:scl enable %scl -- }%make_build
 %if 0%{?rhel} && 0%{?rhel} < 8