Trying to compile frontend 4.0 fails on cygwin

Hello, Seth

checking whether the C compiler works... configure: error: cannot run C
compiled programs.

This usually means, that simple program like:

int main(void) {
  return 0;

failed either to be compiled or to run.

The config.log contains:

The gcc build system is complicated - 'configure' executes just top
level configure and nothing more. 'make' itself executes different
configures in subdirectories, so most probably it was generated by one
of them and you have to check config.log in some subdirectory.

configure:2273:17: gmp.h: No such file or directory

Well, 4.0 doesn't require gmp to be present, as 4.2, so one can treat
this as warning.