There are two problems here:
1) NM has been set to "link -dump -symbols". This is wrong. This setting should
only be valid when the --host platform is win32 and the build platform is
not cygwin. I have an /usr/bin/nm program in $PATH, that works fine for
both 32-bit and 64-bit object files on my platform.
2) global_symbol_pipe has been set to empty.
When I google for
"libtool eval" "link -dump -symbols"
I find dozens of reports of libtool errors that were due to the same
problem: NM being set to "link -dump -symbols" on platforms unrelated to win32
(Linux, MacOS, NetBSD etc.).