Fix compilation issues on RHEL8 and SLES15.5 related to using std::filesystem (#342)

CMakeLists.txt

@@ -109,6 +109,11 @@ if(HIP_FOUND AND Libva_FOUND)
   set(LINK_LIBRARY_LIST ${LINK_LIBRARY_LIST} ${LIBVA_LIBRARY})
   set(LINK_LIBRARY_LIST ${LINK_LIBRARY_LIST} ${LIBVA_DRM_LIBRARY})
 
+  #filesystem: c++ compilers less than equal to 8.5 need explicit link with stdc++fs
+  if (CMAKE_CXX_COMPILER_VERSION VERSION_LESS_EQUAL "8.5")
+    set(LINK_LIBRARY_LIST ${LINK_LIBRARY_LIST} stdc++fs)
+  endif()
+
   # local include files
   include_directories(api src/rocdecode src/parser src/rocdecode/vaapi)
   # source files

samples/videoDecodeBatch/CMakeLists.txt

@@ -74,6 +74,10 @@ if(HIP_FOUND AND FFMPEG_FOUND AND ROCDECODE_FOUND)
     include_directories(${AVUTIL_INCLUDE_DIR} ${AVCODEC_INCLUDE_DIR}
                       ${SWSCALE_INCLUDE_DIR} ${AVFORMAT_INCLUDE_DIR})
     set(LINK_LIBRARY_LIST ${LINK_LIBRARY_LIST} ${FFMPEG_LIBRARIES})
+    #filesystem: c++ compilers less than equal to 8.5 need explicit link with stdc++fs
+    if (CMAKE_CXX_COMPILER_VERSION VERSION_LESS_EQUAL "8.5")
+      set(LINK_LIBRARY_LIST ${LINK_LIBRARY_LIST} stdc++fs)
+    endif()
     # rocDecode and utils
     include_directories (${ROCDECODE_INCLUDE_DIR} ${CMAKE_CURRENT_SOURCE_DIR}/.. ${CMAKE_CURRENT_SOURCE_DIR}/../../utils ${CMAKE_CURRENT_SOURCE_DIR}/../../utils/rocvideodecode)
     set(LINK_LIBRARY_LIST ${LINK_LIBRARY_LIST} ${ROCDECODE_LIBRARY})

src/rocdecode/vaapi/vaapi_videodecoder.h

@@ -29,7 +29,11 @@ THE SOFTWARE.
 #include <fcntl.h>
 #include <unistd.h>
 #include <cstring>
-#include <filesystem>
+#if __cplusplus >= 201703L && __has_include(<filesystem>)
+    #include <filesystem>
+#else
+    #include <experimental/filesystem>
+#endif
 #include <va/va.h>
 #include <va/va_drm.h>
 #include <va/va_drmcommon.h>