perf ui browser: Handle SIGWINCH

To do that we needed to stop using newtForm, as we don't want libnewt to
catch the xterm resize signal.

Remove some more newt calls and instead use the underlying libslang
directly. In time tools/perf will use just libslang.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
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-h1824yjiru5n2ivz4bseizwj@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/perf.h

@@ -183,4 +183,6 @@ struct ip_callchain {
 extern bool perf_host, perf_guest;
 extern const char perf_version_string[];
 
+void pthread__unblock_sigwinch(void);
+
 #endif