Fix ntru avx2 compilation when DOWNLOAD_SODIUM

We don't explicitly have to link against it, but it doesn't hurt *and*
this also pulls in the proper sodium include path, which we do need.

crypto/CMakeLists.txt

@@ -76,6 +76,7 @@ elseif(DOWNLOAD_SODIUM)
   message(STATUS "Sodium >= 1.0.17 not found, but DOWNLOAD_SODIUM specified, so downloading it")
   include(DownloadLibSodium)
   target_link_libraries(${CRYPTOGRAPHY_LIB} PUBLIC sodium_vendor)
+  target_link_libraries(cryptography_avx_lib PUBLIC sodium_vendor)
 else()
   message(FATAL_ERROR "Could not find libsodium >= 1.0.17; either install it on your system or use -DDOWNLOAD_SODIUM=ON to download and build an internal copy")
 endif()