perf tools: Remove needless asm/unistd.h include fixing build in some places

We were including sys/syscall.h and asm/unistd.h, since sys/syscall.h
includes asm/unistd.h, sometimes this leads to the redefinition of
defines, breaking the build.

Noticed on ARC with uCLibc.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Link: https://lkml.kernel.org/n/tip-xjpf80o64i2ko74aj2jih0qg@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/cloexec.c

@@ -7,7 +7,6 @@
 #include "asm/bug.h"
 #include "debug.h"
 #include <unistd.h>
-#include <asm/unistd.h>
 #include <sys/syscall.h>
 
 static unsigned long flag = PERF_FLAG_FD_CLOEXEC;