perf tools: Remove unused pager_use_color variable

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/e540c61b3068761181db6d9b1b3411990bafdb2f.1449548395.git.jpoimboe@redhat.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>