reimplement HIP_INIT as hip_impl::hip_init(), add hip_init() to some of the inlined API (#966)

* reimplement HIP_INIT as a function, expose it as hip_impl::hip_init()
so that it could be called from hipLaunchKernelGGL and other inlined
HIP functions

* Don't call hip_init from ihipPreLaunchKernel

include/hip/hcc_detail/functional_grid_launch.hpp

@@ -189,6 +189,7 @@ inline
 void hipLaunchKernelGGL(F kernel, const dim3& numBlocks, const dim3& dimBlocks,
                         std::uint32_t sharedMemBytes, hipStream_t stream,
                         Args... args) {
+    hip_impl::hip_init();
     auto kernarg = hip_impl::make_kernarg(
         kernel, std::tuple<Args...>{std::move(args)...});
     std::size_t kernarg_size = kernarg.size();
@@ -212,4 +213,4 @@ inline void hipLaunchKernel(F kernel, const dim3& numBlocks, const dim3& dimBloc
                             std::uint32_t groupMemBytes, hipStream_t stream, Args... args) {
     hipLaunchKernelGGL(kernel, numBlocks, dimBlocks, groupMemBytes, stream, hipLaunchParm{},
                        std::move(args)...);
-}
+}