[BUG] tools build: Add HOSTARCH Makefile variable

[Jiada Wang]

Hello,

with commit: 0a943cb10ce7 (tools build: Add HOSTARCH Makefile variable),

the following build failure is seen with ARCH=x86_84 when build for perf

In file included from util/event.c:2:0:
tools/include/uapi/linux/mman.h:4:27: fatal error: uapi/asm/mman.h: No 
such file or directory compilation terminated.

I have submitted a patch which replaces 'ARCH' in perf with 'SRCARCH',
https://lkml.org/lkml/2017/2/27/85
can anyone give your comment?

Thanks in advance

Jiada