perf auxtrace: Include sys/types.h for pid_t

In 754187ad73b73bcb ("perf build: Remove NO_AUXTRACE build option")
sys/types.h was removed, which broke the build in all Alpine Linux
releases, as musl libc has pid_t defined via sys/types.h, add it back.

Fixes: 754187ad73b73bcb ("perf build: Remove NO_AUXTRACE build option")
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>
Reviewed-by: Ian Rogers <[e-mail]>
Signed-off-by: Namhyung Kim <[e-mail]>

tools/perf/util/auxtrace.h

···
 #ifndef __PERF_AUXTRACE_H
 #define __PERF_AUXTRACE_H
 
+#include <sys/types.h>
 #include <stdio.h> // FILE
 #include <linux/perf_event.h>
 #include <linux/types.h>