libelfin autopkgtests fail against newer clang

The autopkgtests are failing due to clang warnings:

101s autopkgtest [09:01:23]: test test-build-libdwarf++: [-----------------------
101s Output from pkg-config --cflags libdwarf++:
101s -I/usr/include/libelfin
101s success: pkg-config call succeeded
101s success: Compilation with cc and c++ produced x.o
101s success: Linking with c++ produced x
101s In file included from x.cpp:1:
101s In file included from /usr/include/libelfin/dwarf/dwarf++.hh:14:
101s /usr/include/libelfin/dwarf/small_vector.hh:96:50: warning: variable length arrays in C++ are a Clang extension [-Wvla-cxx-extension]
101s 96 | char *newbuf = new char[sizeof(T[target])];
101s | ^~~~~~
101s /usr/include/libelfin/dwarf/small_vector.hh:96:50: note: read of non-const variable 'target' is not allowed in a constant expression
101s /usr/include/libelfin/dwarf/small_vector.hh:90:27: note: declared here
101s 90 | size_type target = cap - base;
101s | ^
101s /usr/include/libelfin/dwarf/small_vector.hh:96:50: warning: variable length arrays in C++ are a Clang extension [-Wvla-cxx-extension]
101s 96 | char *newbuf = new char[sizeof(T[target])];
101s | ^~~~~~
101s /usr/include/libelfin/dwarf/small_vector.hh:96:50: note: read of non-const variable 'target' is not allowed in a constant expression
101s /usr/include/libelfin/dwarf/small_vector.hh:90:27: note: declared here
101s 90 | size_type target = cap - base;
101s | ^
102s /usr/include/libelfin/dwarf/small_vector.hh:96:50: warning: variable length arrays in C++ are a Clang extension [-Wvla-cxx-extension]
102s 96 | char *newbuf = new char[sizeof(T[target])];
102s | ^~~~~~
102s /usr/include/libelfin/dwarf/small_vector.hh:68:17: note: in instantiation of member function 'dwarf::small_vector<unsigned long, 6>::reserve' requested here
102s 68 | reserve(osize);
102s | ^
102s /usr/include/libelfin/dwarf/small_vector.hh:43:31: note: in instantiation of member function 'dwarf::small_vector<unsigned long, 6>::operator=' requested here
102s 43 | *this = o;
102s | ^
102s /usr/include/libelfin/dwarf/dwarf++.hh:344:9: note: in instantiation of member function 'dwarf::small_vector<unsigned long, 6>::small_vector' requested here
102s 344 | die(die &&o) = default;
102s | ^
102s /usr/include/libelfin/dwarf/small_vector.hh:96:50: note: read of non-const variable 'target' is not allowed in a constant expression
102s 96 | char *newbuf = new char[sizeof(T[target])];
102s | ^
102s /usr/include/libelfin/dwarf/small_vector.hh:90:27: note: declared here
102s 90 | size_type target = cap - base;
102s | ^
102s 3 warnings generated.
102s success: Compilation with clang and clang++ produced x.o
102s success: Linking with clang++ produced x
102s info: test exiting
102s autopkgtest [09:01:24]: test test-build-libdwarf++: -----------------------]
102s autopkgtest [09:01:24]: test test-build-libdwarf++: - - - - - - - - - - results - - - - - - - - - -
102s test-build-libdwarf++ FAIL stderr: In file included from x.cpp:1:
102s autopkgtest [09:01:24]: test test-build-libdwarf++: - - - - - - - - - - stderr - - - - - - - - - -
102s In file included from x.cpp:1:
102s In file included from /usr/include/libelfin/dwarf/dwarf++.hh:14:
102s /usr/include/libelfin/dwarf/small_vector.hh:96:50: warning: variable length arrays in C++ are a Clang extension [-Wvla-cxx-extension]
102s 96 | char *newbuf = new char[sizeof(T[target])];
102s | ^~~~~~
102s /usr/include/libelfin/dwarf/small_vector.hh:96:50: note: read of non-const variable 'target' is not allowed in a constant expression
102s /usr/include/libelfin/dwarf/small_vector.hh:90:27: note: declared here
102s 90 | size_type target = cap - base;
102s | ^
102s /usr/include/libelfin/dwarf/small_vector.hh:96:50: warning: variable length arrays in C++ are a Clang extension [-Wvla-cxx-extension]
102s 96 | char *newbuf = new char[sizeof(T[target])];
102s | ^~~~~~
102s /usr/include/libelfin/dwarf/small_vector.hh:96:50: note: read of non-const variable 'target' is not allowed in a constant expression
102s /usr/include/libelfin/dwarf/small_vector.hh:90:27: note: declared here
102s 90 | size_type target = cap - base;
102s | ^
102s /usr/include/libelfin/dwarf/small_vector.hh:96:50: warning: variable length arrays in C++ are a Clang extension [-Wvla-cxx-extension]
102s 96 | char *newbuf = new char[sizeof(T[target])];
102s | ^~~~~~
102s /usr/include/libelfin/dwarf/small_vector.hh:68:17: note: in instantiation of member function 'dwarf::small_vector<unsigned long, 6>::reserve' requested here
102s 68 | reserve(osize);
102s | ^
102s /usr/include/libelfin/dwarf/small_vector.hh:43:31: note: in instantiation of member function 'dwarf::small_vector<unsigned long, 6>::operator=' requested here
102s 43 | *this = o;
102s | ^
102s /usr/include/libelfin/dwarf/dwarf++.hh:344:9: note: in instantiation of member function 'dwarf::small_vector<unsigned long, 6>::small_vector' requested here
102s 344 | die(die &&o) = default;
102s | ^
102s /usr/include/libelfin/dwarf/small_vector.hh:96:50: note: read of non-const variable 'target' is not allowed in a constant expression
102s 96 | char *newbuf = new char[sizeof(T[target])];
102s | ^
102s /usr/include/libelfin/dwarf/small_vector.hh:90:27: note: declared here
102s 90 | size_type target = cap - base;
102s | ^
102s 3 warnings generated.