compile failed with t3.c

[Yi Li]

Hi list,
   When i try to compile examples/bpf/t3.c with command annotated in
that source file, got this error:
[root at server bpf]# clang -O2 -U __GNUC__ -target bpf
-Wno-int-to-void-pointer-cast -c t3.c
In file included from t3.c:27:
In file included from /usr/local/include/rte_mbuf_core.h:22:
/usr/local/include/rte_byteorder.h:30:16: error: invalid output
constraint '=Q' in asm
                      : [x1] "=Q" (x)
                             ^
1 error generated.
[root at server bpf]#

   I think this should be the root cause as noted linux kernel
Documentation/bpf/bpf_devel_QA.txt

BPF programs may recursively include header file(s) with file scope
inline assembly codes. The default target can handle this well, while
bpf target may fail if bpf backend assembler does not understand these
assembly codes, which is true in most cases.