Use Hunter to download zstd

CMakeLists.txt

@@ -731,18 +731,28 @@ endif()
 option(CURL_ZSTD "Set to ON to enable building curl with zstd support." OFF)
 set(HAVE_ZSTD OFF)
 if(CURL_ZSTD)
-  find_package(Zstd REQUIRED)
-  if (NOT DEFINED HAVE_ZSTD_CREATEDSTREAM)
-    cmake_push_check_state()
-    set(CMAKE_REQUIRED_INCLUDES ${Zstd_INCLUDE_DIRS})
-    set(CMAKE_REQUIRED_LIBRARIES ${Zstd_LIBRARIES})
-    check_symbol_exists(ZSTD_createDStream "zstd.h" HAVE_ZSTD_CREATEDSTREAM)
-    cmake_pop_check_state()
-  endif()
-  if(Zstd_FOUND AND HAVE_ZSTD_CREATEDSTREAM)
-    set(HAVE_ZSTD ON)
-    list(APPEND CURL_LIBS ${Zstd_LIBRARIES})
-    include_directories(${Zstd_INCLUDE_DIRS})
+  hunter_add_package(zstd)
+  if(HUNTER_ENABLED)
+    find_package(zstd REQUIRED)
+    if(Zstd_FOUND AND HAVE_ZSTD_CREATEDSTREAM)
+      set(HAVE_ZSTD ON)
+      list(APPEND CURL_LIBS zstd::libzstd_static)
+      include_directories(${ZSTD_INCLUDE_DIRS})
+    endif()
+  else()
+    find_package(Zstd REQUIRED)
+    if (NOT DEFINED HAVE_ZSTD_CREATEDSTREAM)
+      cmake_push_check_state()
+      set(CMAKE_REQUIRED_INCLUDES ${Zstd_INCLUDE_DIRS})
+      set(CMAKE_REQUIRED_LIBRARIES ${Zstd_LIBRARIES})
+      check_symbol_exists(ZSTD_createDStream "zstd.h" HAVE_ZSTD_CREATEDSTREAM)
+      cmake_pop_check_state()
+    endif()
+    if(Zstd_FOUND AND HAVE_ZSTD_CREATEDSTREAM)
+      set(HAVE_ZSTD ON)
+      list(APPEND CURL_LIBS ${Zstd_LIBRARIES})
+      include_directories(${Zstd_INCLUDE_DIRS})
+    endif()
   endif()
 endif()