perf jvmti: Give hints about package names needed to build

Give as examples of package names to install to have this built for
fedora and debian, to help the user a bit.

The part from 'e.g.:' onwards:

No openjdk development package found, please install JDK package, e.g. openjdk-8-jdk, java-1.8.0-openjdk-devel

Cc: Andi Kleen <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Stephane Eranian <[e-mail]>
Cc: William Cohen <[e-mail]>
Link: https://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/Makefile.config

···
   ifeq ($(feature-jvmti), 1)
     $(call detected_var,JDIR)
   else
-    $(warning No openjdk development package found, please install JDK package)
+    $(warning No openjdk development package found, please install JDK package, e.g. openjdk-8-jdk, java-1.8.0-openjdk-devel)
     NO_JVMTI := 1
   endif
 endif