SET(CURL_ZLIB OFF) (#99)

More recent Alpine images were failing to build nginx-datadog
due to libz.so being in a different location on the file system
than expected by the build produced by CMake.

We do not want to build (libcurl) with zlib anyway. Looking around,
I found that CURL_ZLIB was needed in addition to (or instead of?)
USE_ZLIB.

Author: dgoffredo

cmake/curl.cmake

@@ -11,6 +11,7 @@ SET(HTTP_ONLY ON)
 SET(CURL_ENABLE_SSL OFF)
 SET(CURL_BROTLI OFF)
 SET(CURL_ZSTD OFF)
+SET(CURL_ZLIB OFF)
 SET(USE_ZLIB OFF)
 SET(USE_LIBIDN2 OFF)
 SET(CURL_USE_LIBSSH2 OFF)