If both LIBBPF and DWARF are detected, it is possible to create prologue
for eBPF programs to help them access kernel data. HAVE_BPF_PROLOGUE and
CONFIG_BPF_PROLOGUE are added as flags for this feature.

PERF_HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET is introduced in commit
63ab024a ("perf tools:
regs_query_register_offset() infrastructure"), which indicates that an
architecture supports converting name of a register to its offset in
'struct pt_regs'. Without this support, BPF_PROLOGUE should be turned
off.
Signed-off-by: NWang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1447675815-166222-9-git-send-email-wangnan0@huawei.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>