xdp10.p4: counter support

[williamtu]

add xdp10.p4, compile and there are missing definitions for

clang \
	-D__KERNEL__ -D__ASM_SYSREG_H -Wno-unused-value -Wno-pointer-sign \
	-Wno-compare-distinct-pointer-types \
	-Wno-gnu-variable-sized-type-not-at-end \
	-Wno-tautological-compare \
	-O2 -emit-llvm -g -c xdp10.c -o -| llc -march=bpf -filetype=obj -o xdp10.o
xdp10.c:173:21: error: use of undeclared identifier 'counters_value'
                    counters_value *value;
                    ^
xdp10.c:173:37: error: use of undeclared identifier 'value'
                    counters_value *value;

adding the following in xdp10.h solves the problem

typedef u32 counters_value;
typedef u32 counters_key;

[mihaibudiu]

This issue should be solved.

[williamtu]

looks good, thanks.