perf llvm: Return -ENOMEM when asprintf() fails

perf llvm: Return -ENOMEM when asprintf() fails

Zhihao sent a patch but it made llvm__compile_bpf() return what
asprintf() returns on error, which is just -1, but since this function
returns -errno, fix it by returning -ENOMEM for this case instead.

Fixes: 2b325e6c4b82d8 ("perf llvm: Allow passing options to llc ...")
Fixes: fc230d9bf8a778 ("perf llvm: Display eBPF compiling command ...")
Reported-by: Hulk Robot <hulkci@huawei.com>
Reported-by: Zhihao Cheng <chengzhihao1@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Yu Kuai <yukuai3@huawei.com>
Cc: clang-built-linux@googlegroups.com
Link: http://lore.kernel.org/lkml/20210609115945.2193194-1-chengzhihao1@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>