Benchmark.pmの方にも
use bignum;
を入れると違うエラーになりました
runloop unable to compile '': Constant(undef): $^H{integer} is not defined at (e
val 10) line 1, at end of line
Constant(undef): $^H{float} is not defined at (eval 10) line 1, at end of line

code: sub { for (1 .. 10000000000000) { local $_; package main; ;} }
at F:\perl\test.pl line 7

こりゃお手上げじゃー