using GRHydro::reconstruct_Wv with recon_method = WENO segfaults

revision 587 of GRHydro intoruced a regression and causes the code to abort with a segfault if GRHydro::reconstruct_Wv = yes and GRHydro:recon_method = WENO are both set.

The problem is access to an uninitialized pointer. The attached patch removes the pointers and moves the function call using the pointer inside of a set of if statements which makes the usage of pointer unnecessary.

Keyword: GRhydro
Keyword: backport