Cygwin64 pil64 build log -- it's failing at building `ext` (i.e. at `cc -o ../lib/ext emu.ext.o`)

cygwin64-pil64-build.log

picoLisp-3.1.9.12 $ echo "$(uname -o) $(uname -r) $(uname -m)"
Cygwin 1.7.35(0.287/5/3) x86_64
picoLisp-3.1.9.12 $ (cd src64; make)
emu.ext.o:emu.ext.c:(.rdata$.refptr.FirstLib[.refptr.FirstLib]+0x0): undefined reference to `FirstLib'
emu.ext.o:emu.ext.c:(.rdata$.refptr.Z[.refptr.Z]+0x0): undefined reference to `Z'
emu.ext.o:emu.ext.c:(.rdata$.refptr.X[.refptr.X]+0x0): undefined reference to `X'
emu.ext.o:emu.ext.c:(.rdata$.refptr.C[.refptr.C]+0x0): undefined reference to `C'
emu.ext.o:emu.ext.c:(.rdata$.refptr.Carry[.refptr.Carry]+0x0): undefined reference to `Carry'
emu.ext.o:emu.ext.c:(.rdata$.refptr.A[.refptr.A]+0x0): undefined reference to `A'
emu.ext.o:emu.ext.c:(.rdata$.refptr.L[.refptr.L]+0x0): undefined reference to `L'
emu.ext.o:emu.ext.c:(.rdata$.refptr.S[.refptr.S]+0x0): undefined reference to `S'
emu.ext.o:emu.ext.c:(.rdata$.refptr.E[.refptr.E]+0x0): undefined reference to `E'
emu.ext.o:emu.ext.c:(.rdata$.refptr.Result[.refptr.Result]+0x0): undefined reference to `Result'
emu.ext.o:emu.ext.c:(.rdata$.refptr.PC[.refptr.PC]+0x0): undefined reference to `PC'
/usr/lib/gcc/x86_64-pc-cygwin/4.9.2/../../../../lib/libcygwin.a(libcmain.o): In function `main':
/usr/src/debug/cygwin-1.7.35-1/winsup/cygwin/lib/libcmain.c:39: undefined reference to `WinMain'
/usr/src/debug/cygwin-1.7.35-1/winsup/cygwin/lib/libcmain.c:39:(.text.startup+0x7e): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `WinMain'
collect2: error: ld returned 1 exit status
Makefile:114: recipe for target '../lib/ext' failed
make: *** [../lib/ext] Error 1