perf tools: Update makefile message for installing slang devel package

In case of missing library (libslang), give hint to install library
(libslang2-dev), since libslang-dev is not provided by Ubuntu.
Signed-off-by: Neeraj Badlani <neerajbadlani@gmail.com>
Link: http://lkml.kernel.org/r/1467035997-9100-1-git-send-email-neerajbadlani@gmail.com
[ removed excessive 'or' usage ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/config/Makefile

@@ -482,7 +482,7 @@ endif
 
 ifndef NO_SLANG
   ifneq ($(feature-libslang), 1)
-    msg := $(warning slang not found, disables TUI support. Please install slang-devel or libslang-dev);
+    msg := $(warning slang not found, disables TUI support. Please install slang-devel, libslang-dev or libslang2-dev);
     NO_SLANG := 1
   else
     # Fedora has /usr/include/slang/slang.h, but ubuntu /usr/include/slang.h