[buildessential] update gcc version to 7.3.0 (#2277)

* [buildessential] update gcc version to 7.3.0

* upgrade gcc to 7.3.0, please remove gcc first

packages/buildessential.rb

@@ -3,11 +3,11 @@ require 'package'
 class Buildessential < Package
   description 'A collection of tools essential to compile and build software.'
   homepage ''
-  version '1.0-3'
+  version '1.1'
 
   is_fake
 
-  depends_on 'gcc'
+  depends_on 'gcc7'
   depends_on 'linuxheaders'
   depends_on 'make'
   depends_on 'pkgconfig'