HDFS-16665. Fix duplicate sources for HDFS test (#4573)

* The library target hdfspp_test_shim_static is
  built using the following sources, which
  causes duplicate symbols to be defined -
  - hdfs_shim.c
  - ${LIBHDFSPP_BINDING_C}/hdfs.cc
* ${LIBHDFSPP_BINDING_C}/hdfs.cc is redundant
  and removing this fixes the issue.

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfspp/tests/CMakeLists.txt

@@ -150,7 +150,7 @@ include_directories (
     ${CMAKE_CURRENT_SOURCE_DIR}/../../libhdfs-tests/
 )
 
-add_library(hdfspp_test_shim_static STATIC $<TARGET_OBJECTS:x_platform_obj> hdfs_shim.c libhdfs_wrapper.c libhdfspp_wrapper.cc ${LIBHDFSPP_BINDING_C}/hdfs.cc)
+add_library(hdfspp_test_shim_static STATIC $<TARGET_OBJECTS:x_platform_obj> hdfs_shim.c libhdfs_wrapper.c libhdfspp_wrapper.cc)
 add_dependencies(hdfspp_test_shim_static proto)
 
 add_library(hdfspp_test_static STATIC $<TARGET_OBJECTS:x_platform_obj> ${LIBHDFSPP_BINDING_C}/hdfs.cc)