Improve brew config for Linuxbrew
Improve brew config for Linuxbrew

For example:

Kernel: Linux 2.6.18-371.1.2.el5 x86_64 GNU/Linux
OS: CentOS release 5.11 (Final)
OS glibc: 2.5
OS gcc: 4.1.2
Linuxbrew glibc: 2.19
Linuxbrew gcc: 5.3.0

Closes Linuxbrew/linuxbrew#684

Linuxbrew/brew,rwhogg/brew,hanxue/linuxbrew,hanxue/linuxbrew,Linuxbrew/brew,Linuxbrew/brew,rwhogg/brew,maxim-belkin/brew,Linuxbrew/brew,maxim-belkin/brew,maxim-belkin/brew,hanxue/linuxbrew,rwhogg/brew