tools lib: Adopt zalloc()/zfree() from tools/perf

Eroding a bit more the tools/perf/util/util.h hodpodge header.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-natazosyn9rwjka25tvcnyi0@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/env.c

@@ -2,7 +2,7 @@
 #include "cpumap.h"
 #include "env.h"
 #include <linux/ctype.h>
-#include "util.h"
+#include <linux/zalloc.h>
 #include "bpf-event.h"
 #include <errno.h>
 #include <sys/utsname.h>