llvm: add 3.9.0 bottle for Linuxbrew.
llvm: add 3.9.0 bottle for Linuxbrew.

Updates for Linux:

1. Add a non-relocatable bottle (/home/linuxbrew/.linuxbrew)
2. Depend on: gcc, [glibc, binutils]
3. Require C++11 compiler (`needs :cxx11`)
4. Add `#{HOMEBREW_PREFIX}/opt/glibc/lib` to the list of directories searched by default by clang
5. Specify CMAKE_CXX_LINK_FLAGS and CLANG_DEFAULT_CXX_STDLIB on Linux

Closes Linuxbrew/homebrew-core#1157
Closes Linuxbrew/homebrew-core#1202
Closes Linuxbrew/homebrew-core#1389 

Signed-off-by: Maxim Belkin <032baa6ccf1d4eaa4536fc4f9b83b9a1f593449a@gmail.com>
Linuxbrew/homebrew-core,LinuxbrewTestBot/homebrew-core,rwhogg/homebrew-core,rwhogg/homebrew-core,maxim-belkin/homebrew-core,LinuxbrewTestBot/homebrew-core,Linuxbrew/homebrew-core,maxim-belkin/homebrew-core