Use CMake FetchContent for curl

Add and expose curl as a cmake target

CMakeLists.txt

@@ -64,17 +64,7 @@ if (BUILD_TESTING)
   set(CMAKE_BUILD_TYPE "Debug")
 endif()
 
-include (ExternalProject)
-ExternalProject_Add(curl
-  URL "https://github.com/curl/curl/releases/download/curl-7_85_0/curl-7.85.0.tar.gz"
-  URL_MD5 "4e9eb4f434e9be889e510f038754d3de"
-  BUILD_IN_SOURCE 1
-  DOWNLOAD_EXTRACT_TIMESTAMP 0
-  SOURCE_DIR ${CMAKE_BINARY_DIR}/curl
-  CONFIGURE_COMMAND ${CMAKE_BINARY_DIR}/curl/configure --prefix=${CMAKE_BINARY_DIR} --disable-ftp --disable-ldap --disable-dict --disable-telnet --disable-tftp --disable-pop3 --disable-smtp --disable-gopher --without-ssl --disable-crypto-auth --without-axtls --without-zlib --disable-rtsp --enable-shared=no --enable-static=yes --with-pic --without-brotli --without-libidn2
-  BUILD_COMMAND make -j${MAKE_JOB_COUNT}
-  INSTALL_COMMAND make install
-)
+include(cmake/curl.cmake)
 
 if (APPLE)
   find_library(COREFOUNDATION_LIBRARY CoreFoundation)
@@ -206,16 +196,13 @@ target_sources(dd_trace_cpp-objects PUBLIC
   src/datadog/w3c_propagation.h
 )
 
-add_dependencies(dd_trace_cpp-objects curl)
-
-# Make the build libcurl visible.
-include_directories(${CMAKE_BINARY_DIR}/include)
+add_dependencies(dd_trace_cpp-objects libcurl)
 
 # Linking this library requires libcurl and threads.
 find_package(Threads REQUIRED)
 target_link_libraries(dd_trace_cpp-objects
   PUBLIC
-    ${CMAKE_BINARY_DIR}/lib/libcurl.a
+    libcurl
   PUBLIC
     Threads::Threads
     ${COVERAGE_LIBRARIES}

cmake/curl.cmake

@@ -0,0 +1,23 @@
+
+include(FetchContent)
+
+# No need to build curl executable
+SET(BUILD_CURL_EXE OFF)
+SET(BUILD_SHARED_LIBS OFF)
+SET(BUILD_STATIC_LIBS ON)
+
+# Disables all protocols except HTTP
+SET(HTTP_ONLY ON)
+SET(CURL_ENABLE_SSL OFF)
+SET(CURL_BROTLI OFF)
+SET(CURL_ZSTD OFF)
+SET(USE_ZLIB OFF)
+SET(USE_LIBIDN2 OFF)
+
+FetchContent_Declare(
+  curl
+  URL "https://github.com/curl/curl/releases/download/curl-7_85_0/curl-7.85.0.tar.gz"
+  URL_MD5 "4e9eb4f434e9be889e510f038754d3de"
+)
+
+FetchContent_MakeAvailable(curl)