Fix the misplaced libcurl in CMake (rapidsai#587)

This PR fixes a CMake bug introduced in rapidsai#581 where `libcurl` is unconditionally compiled.

Authors:
  - Tianyu Liu (https://github.com/kingcrimsontianyu)

Approvers:
  - Kyle Edwards (https://github.com/KyleFromNVIDIA)
  - Bradley Dice (https://github.com/bdice)
  - Alessandro Bellina (https://github.com/abellina)

URL: rapidsai#587

cpp/CMakeLists.txt

@@ -143,14 +143,13 @@ set(SOURCES
     "src/posix_io.cpp"
     "src/shim/cuda.cpp"
     "src/shim/cufile.cpp"
-    "src/shim/libcurl.cpp"
     "src/shim/utils.cpp"
     "src/stream.cpp"
     "src/utils.cpp"
 )
 
 if(KvikIO_REMOTE_SUPPORT)
-  list(APPEND SOURCES "src/remote_handle.cpp")
+  list(APPEND SOURCES "src/remote_handle.cpp" "src/shim/libcurl.cpp")
 endif()
 
 add_library(kvikio ${SOURCES})