Some symbols reference libcore panicking functions

[alexcrichton]

I was curious to give out the new libm-for-wasm bits a spin and got a small example working, but to my surprise it imported a few functions from the environment:

  (import "env" "_ZN4core9panicking18panic_bounds_check17h5517321e0731ca2aE" (func $core::panicking::panic_bounds_check::h5517321e0731ca2a (type $t0)))
  (import "env" "_ZN4core9panicking5panic17he062e0bd3417b514E" (func $core::panicking::panic::he062e0bd3417b514 (type $t1)))

which isn't good for wasm!

It looks like these are mostly around the rem_pio2_large function (and family of functions from the looks of it)