Potential incomplete updated GNUMakefile

[yeanment]

In the PeleC and PeleLMeX code, the environmental variable HOSTCC seems not to be used in Amrex anymore. Only in the PelePhysic, the HOSTCC is defined in PelePhysics/ThirdParty/Make.ThirdParty. However, in the Make.PeleLMeX or Make.PeleC file, this variable is still used to build sundials. In the case of compiling code with CUDA support, this potentially leads to unexpected errors in finding the right compiler, when using cuda and a non-gcc comiler.