16.10 has modified gcc to compile with -pie by default.  That just must get
in the way of unexec.

Search "gcc" in https://wiki.ubuntu.com/YakketyYak/ReleaseNotes,

I have tried this successfully (both emacs-25 and master):

1. in the git workdir:

$ ./autogen.sh

2. in the build directory:

$ ...../configure CFLAGS=-no-pie <other configure options>

and the binaries built fine.

On topic, it would be nice if there was a string in the binary that told
one how the $(config.status --config), so one could (more) easily rebuild a
binary.  Something like a function (emacs-configure-options).

This has worked with ASLR on (echo 2 > /proc/sys/kernel/randomize_va_space)
and with ASLR off (echo 0 > /proc/sys/kernel/randomize_va_space).

--César