perf tui: Add explicit -lslang option

At least on rawhide using -lnewt is not enough if we use SLang routines
directly, so add an explicit -lslang since we use SLang routines.
Reported-by: NIngo Molnar <mingo@elte.hu>
Tested-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Makefile

@@ -564,7 +564,7 @@ ifneq ($(shell sh -c "(echo '\#include <newt.h>'; echo 'int main(void) { newtIni
 else
 	# Fedora has /usr/include/slang/slang.h, but ubuntu /usr/include/slang.h
 	BASIC_CFLAGS += -I/usr/include/slang
-	EXTLIBS += -lnewt
+	EXTLIBS += -lnewt -lslang
 	LIB_OBJS += $(OUTPUT)util/newt.o
 endif