docs/linux-setup: Install dependencies for Ubuntu 16.04

Not sure which Ubuntu is used in the installation guide but for the latest LTS release 16.04 we need libtool-bin for
compiling crosstool-NG proper

Merges #46 https://github.com/espressif/esp-idf/pull/46

docs/linux-setup.rst

@@ -83,6 +83,10 @@ In any case, here are the steps to compile the toolchain yourself.
 
         sudo apt-get install gawk gperf grep gettext libncurses-dev python python-dev automake bison flex texinfo help2man libtool
 
+  - Ubuntu 16.04::
+  
+        sudo apt-get install gawk gperf grep gettext python python-dev automake bison flex texinfo help2man libtool libtool-bin
+
   - Debian::
 
         TODO