$ ./configure --with-sysdir=/opt/mingw-w64
configure: WARNING: unrecognized options: --with-sysdir
checking build system type... i686-pc-cygwin
checking host system type... i686-pc-cygwin
checking target system type... i686-pc-cygwin
checking for a BSD-compatible install... /usr/bin/install -c
checking whether build environment is sane... yes
checking for a thread-safe mkdir -p... /usr/bin/mkdir -p
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking how to create a ustar tar archive... cpio
checking for style of include used by make... GNU
checking for gcc... /opt/mingw-w64/bin/i686-w64-mingw32-gcc.exe
checking whether the C compiler works... no
configure: error: in `/cygdrive/z/src/libcaca':
configure: error: C compiler cannot create executables
See `config.log' for more details