Warnings from campHipErrchk

[MrBurmark]

I see warnings with rocm coming from campHipErrchk.
I took a look in the hip headers and with c++17 the hip error type is declared with nodiscard. So while we check the error in campHipErrchk, we still get a warning because the error is returned.

In file included from ../test/resource.cpp:16:
In file included from ../include/camp/resource.hpp:27:
../include/camp/resource/hip.hpp:33:11: warning: ignoring return value of function declared with 'nodiscard' attribute [-Wunused-result]
         campHipErrchk(hipGetDevice(&prev_device));
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../include/camp/defines.hpp:196:28: note: expanded from macro 'campHipErrchk'
#define campHipErrchk(ans) ::camp::hipAssert((ans), #ans, __FILE__, __LINE__)
                           ^~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~