build failed on cygwin

[mintty]

./build-djgpp.sh 5.1.0 fails with:

In file included from /usr/lib/gcc/x86_64-pc-cygwin/11/include/c++/bits/stl_algobase.h:64,
from /usr/lib/gcc/x86_64-pc-cygwin/11/include/c++/bits/char_traits.h:39,
from /usr/lib/gcc/x86_64-pc-cygwin/11/include/c++/string:40,
from ../../gnu/gcc-5.10/gcc/system.h:201,
from ../../gnu/gcc-5.10/gcc/genpreds.c:24:
/usr/lib/gcc/x86_64-pc-cygwin/11/include/c++/bits/stl_pair.h:211:12: note: ‘struct std::pair<unsigned int, const char*>’ declared here
211 | struct pair
| ^~~~
make[2]: *** [Makefile:2422: build/genpreds.o] Error 1