double instead of CCTK_REAL in two routines in GRHydro

There are two places in GRHydro code that variables are declared using double.

It will be better to use CCTK_REAL instead. It makes it easier to check various things by setting REAL_PRECISION in the config file.

GRHydro/src/GRHydro_Con2PrimM_pt.c: register double ftmp,gtmp; GRHydro/src/GRHydro_Con2PrimM_pt.c: double gam_m1_o_gam = ((gammaeos-1.)/gammaeos);