Disable compile-errors on deprecation warnings, for JNI [skip ci]

[mythrocks]

Disabled compilation failures on JNI native code, for deprecation warnings.
E.g.

../src/strings/utilities.cuh:82:48:   required from ‘auto cudf::strings::detail::make_strings_children(SizeAndExecuteFunction, cudf::size_type, cudf::size_type, rmm::mr::device_memory_resource*, cudaStream_t) [with SizeAndExecuteFunction = cudf::strings::detail::_GLOBAL__N__56_tmpxft_00006cba_00000000_8_backref_re_compute_75_cpp1_ii_c02a6011::backrefs_fn<112>; cudf::size_type = int; cudaStream_t = CUstream_st*]’
../src/strings/replace/backref_re.cu:205:173:   required from here
/home/mithunr/workspace/anaconda2/envs/cudf_dev/include/rmm/thrust_rmm_allocator.h:61:10: warning: ‘rmmError_t rmm::free(void*, cudaStream_t, const char*, unsigned int)’ is deprecated [-Wdeprecated-declarations]
       RMM_FREE(thrust::raw_pointer_cast(ptr), stream);
       ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/mithunr/workspace/anaconda2/envs/cudf_dev/include/rmm/rmm.hpp:192:34: note: declared here

[jlowe]

@kkraus14 @harrism this should be ready to merge into branch-0.13 to fix the JNI build. Thanks!