Add BUILD_BYPRODUCTS to ext/curl (#821)

In order to build this launcher with Ninja, CMake needs to know that libcurl.a is a byproduct of the curl external project.

ext/curl.cmake

@@ -24,6 +24,7 @@ ExternalProject_Add(
         curl_ext
         ${CURL_EXT_PROPERTIES}
         INSTALL_DIR ${CMAKE_BINARY_DIR}/ext/curl
+        BUILD_BYPRODUCTS "${CMAKE_BINARY_DIR}/ext/curl/lib/libcurl.a"
         CMAKE_ARGS "-DCMAKE_INSTALL_PREFIX=${CMAKE_BINARY_DIR}/ext/curl" "-DBUILD_CURL_EXE=OFF" "-DBUILD_SHARED_LIBS=OFF" "-DCURL_STATICLIB=ON" "-DCURL_DISABLE_LDAP=ON" "-DCURL_USE_LIBSSH2=OFF" "-DCURL_USE_OPENLDAP=OFF" "-DUSE_LIBIDN2=OFF" "-DCURL_USE_LIBPSL=OFF" "-DENABLE_WEBSOCKETS=ON" "-DCMAKE_INSTALL_LIBDIR=lib" "-DCMAKE_C_FLAGS=${CMAKE_C_FLAGS}" "-DCMAKE_LINK_FLAGS=${CMAKE_LINK_FLAGS}" "-DCMAKE_LIBRARY_ARCHITECTURE=${CMAKE_LIBRARY_ARCHITECTURE}" ${CURL_EXT_EXTRA_OPTIONS}
 )
 file(MAKE_DIRECTORY ${CMAKE_BINARY_DIR}/ext/curl/include/)