Install dependencies on ArchLinux

For Arch Linux, there are prepackaged development binaries available. Install the gmt dependencies with:

# install necessary dependencies
sudo pacman -S base-devel cmake libcurl-gnutls netcdf

# install optional dependencies
sudo pacman -S ninja gdal pcre fftw lapack openblas glib2 ghostscript

# to enable movie-making
sudo pacman -S graphicsmagick ffmpeg

# to enable document viewing via gmt docs
sudo pacman -S xdg-utils

# to enable testing
sudo pacman -S graphicsmagick

# to build the documentation
sudo pacman -S python-sphinx