MDEV-29955: Set path for zlib library with pkg-config

`FindZLIB` module uses variable `ZLIB_ROOT`[1] to look for libraries. By
setting the variable, `FindZLIB` is able to search the libraries that
installed in a non-system path (/workspace/mylib for example).

And when using `z` in `LINK_LIBRARIES()` CMake tries to lookup the
library in system path by default. It doesn't work if the library isn't
installed in the path, and use ${ZLIB_LIBRARY} which set by FindZLIB
solve the issue.

All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license. I am contributing on behalf of my employer Amazon Web
Services.

[1]: https://cmake.org/cmake/help/latest/module/FindZLIB.html#hints

cmake/zlib.cmake

@@ -37,10 +37,14 @@ MACRO (MYSQL_CHECK_ZLIB_WITH_COMPRESS)
   IF(WITH_ZLIB STREQUAL "bundled")
     MYSQL_USE_BUNDLED_ZLIB()
   ELSE()
-    INCLUDE(FindZLIB)
+    FIND_PACKAGE(PkgConfig QUIET)
+    IF(PKG_CONFIG_FOUND AND (COMMAND PKG_GET_VARIABLE) AND (NOT WIN32))
+      PKG_GET_VARIABLE(ZLIB_ROOT zlib prefix)
+    ENDIF()
+    FIND_PACKAGE(ZLIB)
     IF(ZLIB_FOUND)
      INCLUDE(CheckFunctionExists)
-      SET(CMAKE_REQUIRED_LIBRARIES z)
+      SET(CMAKE_REQUIRED_LIBRARIES ${ZLIB_LIBRARIES})
       CHECK_FUNCTION_EXISTS(crc32 HAVE_CRC32)
       CHECK_FUNCTION_EXISTS(compressBound HAVE_COMPRESSBOUND)
       CHECK_FUNCTION_EXISTS(deflateBound HAVE_DEFLATEBOUND)

storage/maria/CMakeLists.txt

@@ -124,7 +124,7 @@ ENDIF()
 IF (CURL_FOUND)
   INCLUDE_DIRECTORIES(${CURL_INCLUDE_DIRS})
   MYSQL_ADD_PLUGIN(s3 ha_s3.cc ${S3_SOURCES} COMPONENT s3-engine
-    LINK_LIBRARIES ${CURL_LIBRARIES} z STORAGE_ENGINE NOT_EMBEDDED CONFIG s3.cnf)
+    LINK_LIBRARIES ${CURL_LIBRARIES} ${ZLIB_LIBRARY} STORAGE_ENGINE NOT_EMBEDDED CONFIG s3.cnf)
 ENDIF()
 
 SET(CPACK_RPM_s3-engine_PACKAGE_SUMMARY "Amazon S3 archival storage engine for MariaDB" PARENT_SCOPE)