perf tools: Remove check for unused PERF_PAGER_IN_USE

PERF_PAGER_IN_USE doesn't seem to be used anywhere, so let's remove it.

This will also make it easier to move pager.c into a separate library.
Signed-off-by: NJosh 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/ed9e8370db9811746dc590544cf48c36dcfb1731.1449965119.git.jpoimboe@redhat.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/pager.c

@@ -85,11 +85,5 @@ void setup_pager(void)
 
 int pager_in_use(void)
 {
-	const char *env;
-
-	if (spawned_pager)
-		return 1;
-
-	env = getenv("PERF_PAGER_IN_USE");
-	return env ? perf_config_bool("PERF_PAGER_IN_USE", env) : 0;
+	return spawned_pager;
 }