Initial implementation based on Math.Pow
[jit] Avoid making generic calls from gsharedvt methods normally, go through the rgctx infrastructure instead. Fixes #21677.
[sgen] Debug option for `clear-at-tlab-creation` nursery clear policy.

With the debug policy, we do clear at TLAB creation, but at GC time, whenever
we would clear with `clear-at-gc`, instead of not clearing, we fill with 0xff.
[sgen] File size limit for binary protocols.

We can now pass a file size limit to the `binary-protocol` option.  It will
create numbered binary protocol files, and only keep the last two around.
This is useful for cases where the only way to reproduce a bug is through
a long run that would otherwise create a protocol that's much too big.
Turns out some devices can have network interfaces without names.

If we encounter such a device we assign it an empty name followed by index number, so that we can
put any number of such devices in the dictionary and report them to the user.

Fixes https://bugzilla.xamarin.com/show_bug.cgi?id=21741
Implemented custom IntPow method for integer exponents
Workaround for decimal (instead of a missing op_Power user-defined operator)
Fixed behavior for nullable decimals - converting them to double via decimal.op_Explicit, not conv.r8
Merge branch 'master' of https://github.com/mono/mono