The respective test that leads to the error message is

chdir('conf') or die "chdir: $!";

open(TST,">compilerok.c") or die "open: $!";
print TST <<'ESQ';
int main () { return 0; }
ESQ
close(TST);

if (system("$Config{'cc'} $flags compilerok.c > compilerok.log 2>&1"))
+ {
  die <<"__EOT__";
...
[download]

so looking into compilerok.log (as it says in the message) might give a clue as to why that simple snippet of C code cannot be compiled.