Update Brewfile for GCC 9 and Homebrew > 2.0

Author: zbeekman

Brewfile

@@ -1,20 +1,19 @@
-# Brewfile to install OpenCoarrays prerequisites with [Homebrew] or [Linuxbrew].
+# Brewfile to install OpenCoarrays prerequisites with [Homebrew].
 #
 # TL;DR: `brew tap homebrew/bundle && brew bundle` to install prerequisites
 #
 # Homebrew for Mac OS X can be installed via:
 # `/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"`
-# Linux brew (lives in userland, no sudo required) can be installed with:
-# `ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Linuxbrew/linuxbrew/go/install)"`
+# Homebrew for Linux (lives in userland, no sudo required) can be installed with:
+# `sh -c "$(curl -fsSL https://raw.githubusercontent.com/Linuxbrew/install/master/install.sh)"`
 #
 # Once Homebrew/Linuxbrew is installed, execute the following commands to install the required prerequisites:
 # `brew tap homebrew/bundle && brew bundle`
 #
 
 brew 'cmake'
 brew 'gcc'
-brew 'mpich', args: ['cc=gcc-8', 'build-from-source']
-brew 'opencoarrays', args: ['cc=gcc-8', 'build-from-source']
+brew 'mpich', args: ['cc=gcc-9', 'build-from-source']
+# brew 'opencoarrays', args: ['cc=gcc-9', 'build-from-source']
 
 # [Homebrew]: http://brew.sh
-# [Linuxbrew]: http://linuxbrew.sh