perf build: Remove uneeded variables

perf build: Remove uneeded variables

Removing uneeded variables from Makefile.perf:

  BUILTIN_OBJS LIB_OBJS GTK_OBJS
  - objects are now hold by in the build Makefiles

  LIB_H
  - header dependencies iare now handled by Build
    framework

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Tested-by: Will Deacon <will.deacon@arm.com>
Cc: Alexis Berlemont <alexis.berlemont@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-o85k0klhwqh3fmvryfgcpr95@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>