Install latest GMT on ArchLinux

It's easier to manage installed content and dependencies than directly building and manually make install in ArchLinux.

# Full update system packages first
sudo pacman -Syu

# Install tools for building AUR packages
sudo pacman -S base-devel

# Use git command to clone non-official AUR repo of gmt
# Here are two options. **You just have to clone one of them:**
# If you encounter some problems in those repo,
# you can report to the authors first, or choose another one to clone
git clone https://aur.archlinux.org/gmt.git

# alternative repo, for testing stable/rc release in version 6.x branch
git clone https://aur.archlinux.org/gmt6.git gmt

# Optional recommended packages
git clone https://aur.archlinux.org/gmt-coast.git
git clone https://aur.archlinux.org/gmt-cpt-city.git
git clone https://aur.archlinux.org/gmt-dcw.git

# use makepkg to build packages and use pacman to install
cd gmt
makepkg -sc
sudo pacman -U *.pkg.tar.xz

Note: Binary packages of gmt are still not available in ArchlinuxCN repo yet.