问在Github Actions windows msys2上，configure找不到icu

EN

C:\msys64\msys2_shell.cmd -mingw64 -defterm -here -full-path -no-start -shell bash scripts/cibw_before_all_windows.sh

pacman -S --noconfirm --needed  \
           bison  \
           flex  \
           icu-devel  \
           swig

export CPPFLAGS="-I/c/msys2/usr/include ${CPPFLAGS}"
export LDFLAGS="-L/c/msys2/usr/lib ${LDFLAGS}"
export PATH="/c/msys2/usr/bin/:${PATH}"
export PKG_CONFIG_PATH="/c/msys2/usr/lib/pkgconfig:${PKG_CONFIG_PATH}"


cd hfst_src/
autoreconf -fvi
./configure --with-unicode-handler=icu
make
make check V=1 VERBOSE=1
make install
cd ..

python setup.py build_ext

...
  checking for ld used by g++... C:/msys64/mingw64/x86_64-w64-mingw32/bin/ld.exe
  checking if the linker (C:/msys64/mingw64/x86_64-w64-mingw32/bin/ld.exe) is GNU ld... yes
  checking whether the g++ linker (C:/msys64/mingw64/x86_64-w64-mingw32/bin/ld.exe) supports shared libraries... yes
  checking for g++ option to produce PIC... -DDLL_EXPORT -DPIC
  checking if g++ PIC flag -DDLL_EXPORT -DPIC works... yes
  checking if g++ static flag -static works... yes
  checking if g++ supports -c -o file.o... yes
  checking if g++ supports -c -o file.o... (cached) yes
  checking whether the g++ linker (C:/msys64/mingw64/x86_64-w64-mingw32/bin/ld.exe) supports shared libraries... yes
  checking dynamic linker characteristics... Win32 ld.exe
  checking how to hardcode library paths into programs... immediate
  checking for gawk... (cached) gawk
  checking how to run the C preprocessor... gcc -E
  checking for bison... bison -y
  checking for flex... flex
  checking for lex output file root... lex.yy
  checking for lex library... none needed
  checking for library containing yywrap... no
  checking whether yytext is a pointer... yes
  checking for getopts... false
  checking for a Python interpreter with version >= 3.0... python
  checking for python... /mingw64/bin/python
  checking for python version... 3.8
  checking for python platform... win32
  checking for python script directory... ${prefix}/lib/python3.8/site-packages
  checking for python extension module directory... ${exec_prefix}/lib/python3.8/site-packages
  configure: WARNING: Building hfst successfully requires flex newer than 2.5.33 on some platforms. Unless you are building with pre-flex-generated sources, building will probably fail.
  checking whether ln -s works... no, using cp -pR
  checking whether make sets $(MAKE)... (cached) yes
  checking for doxygen... no
  checking for main in -ldl... no
  checking for main in -lpthread... yes
  checking for main in -lm... yes
  checking for ncurses.h... no
  checking for curses.h... no
  checking for termcap.h... yes
  checking for tgetent in -ltermcap... yes
  checking for icu-config... /usr/bin/icu-config
  checking for pkg-config... /mingw64/bin/pkg-config
  ### icu-config: Can't find /usr/lib/msys-icuuc68.dll - ICU prefix is wrong.
  ###      Try the --prefix= option 
  ###      or --detect-prefix
  ###      (If you want to disable this check, use  the --noverify option)
  ### icu-config: Exitting.
  expr: syntax error: unexpected argument '50'
  configure: error: in `/d/a/hfst-python/hfst-python/hfst_src':
  configure: error: --with-unicode-handler=icu requested but icu>=50 not found
  See `config.log' for more details
  Error: Command C:\msys64\msys2_shell.cmd -mingw64 -defterm -here -full-path -no-start -shell bash scripts/cibw_before_all_windows.sh failed with code 1. None

bison-3.7.4-1
flex-2.6.4-1
icu-devel-68.2-1
swig-4.0.2-1