perf tools: Disable JVMTI if no ELF support available

perf tools: Disable JVMTI if no ELF support available

The build of JVMTI depends on LIBELF (-lelf). Make Makefile.conf
check this dependendancy and notify user when not present.

v2: Comma nitpicking.

Signed-off-by: David Carrillo-Cisneros <davidcc@google.com>
Tested-by: Kim Phillips <kim.phillips@arm.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Simon Que <sque@chromium.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/20170412170745.26620-1-davidcc@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>