perf tools, x86: Build perf on older user-space as well

On ancient systems I get this build failure:

  util/../../../arch/x86/include/asm/unistd.h:67:29: error: asm/unistd_64.h: No such file or directory
  In file included from util/cache.h:7,
                   from builtin-test.c:8:
  util/../perf.h: In function ‘sys_perf_event_open’:In file included from util/../perf.h:16
  perf.h:170: error: ‘__NR_perf_event_open’ undeclared (first use in this function)

The reason is that this old system does not have the split
unistd.h headers yet, from which to pick up the syscall
definitions.

Add the syscall numbers to the already existing i386 and x86_64
blocks in perf.h, and also provide empty include file stubs.

With this patch perf builds and works fine on 5 years old
user-space as well.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: http://lkml.kernel.org/n/tip-jctwg64le1w47tuaoeyftsg9@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Makefile

@@ -249,6 +249,8 @@ LIB_H += util/include/asm/uaccess.h
 LIB_H += util/include/dwarf-regs.h
 LIB_H += util/include/asm/dwarf2.h
 LIB_H += util/include/asm/cpufeature.h
+LIB_H += util/include/asm/unistd_32.h
+LIB_H += util/include/asm/unistd_64.h
 LIB_H += perf.h
 LIB_H += util/annotate.h
 LIB_H += util/cache.h

tools/perf/perf.h

@@ -10,13 +10,19 @@ void get_term_dimensions(struct winsize *ws);
 #define rmb()		asm volatile("lock; addl $0,0(%%esp)" ::: "memory")
 #define cpu_relax()	asm volatile("rep; nop" ::: "memory");
 #define CPUINFO_PROC	"model name"
+#ifndef __NR_perf_event_open
+# define __NR_perf_event_open 336
+#endif
 #endif
 
 #if defined(__x86_64__)
 #include "../../arch/x86/include/asm/unistd.h"
 #define rmb()		asm volatile("lfence" ::: "memory")
 #define cpu_relax()	asm volatile("rep; nop" ::: "memory");
 #define CPUINFO_PROC	"model name"
+#ifndef __NR_perf_event_open
+# define __NR_perf_event_open 298
+#endif
 #endif
 
 #ifdef __powerpc__

tools/perf/util/include/asm/unistd_32.h

@@ -0,0 +1 @@
+

tools/perf/util/include/asm/unistd_64.h

@@ -0,0 +1 @@
+