gcc and -flto

[Marco Atzeri]

Hi Achim, Jonathan,

noted on latest guile 3.0.8

this problem

Cygwin runtime failure: 
/pub/devel/guile/guile30/guile3.0-3.0.8-1.x86_64/build/libguile/.libs/guile.exe: 
Invalid relocation.  Offset 0x45a4eb486 at address 0x100401086 doesn't 
fit into 32 bits

goes away removing the `-flto` from CFLAGS

What is strange is that from documentation
https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html

it should be only for ELF, but it seems doing something wrong
on Cygwin

Reported here just in case someone else hit the same problem.

Regards
Marco