Auto merge of #19873 - jonleighton:harfbuzz-dependency, r=jdm

Add harfbuzz dependency to README.md

I tried to build on a freshly installed Fedora 27 system and needed to
install this package.

I've added equivalent packages for other systems, although haven't
actually tested on those systems. (I note that the package was already
listed for openSUSE.)

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README.md

@@ -82,7 +82,8 @@ sudo apt install git curl freeglut3-dev autoconf libx11-dev \
     libfreetype6-dev libgl1-mesa-dri libglib2.0-dev xorg-dev \
     gperf g++ build-essential cmake virtualenv python-pip \
     libssl1.0-dev libbz2-dev libosmesa6-dev libxmu6 libxmu-dev \
-    libglu1-mesa-dev libgles2-mesa-dev libegl1-mesa-dev libdbus-1-dev
+    libglu1-mesa-dev libgles2-mesa-dev libegl1-mesa-dev libdbus-1-dev \
+    libharfbuzz-dev ccache
 ```
 
 If you using a version prior to **Ubuntu 17.04** or **Debian Sid**, replace `libssl1.0-dev` with `libssl-dev`.
@@ -98,7 +99,7 @@ sudo dnf install curl freeglut-devel libtool gcc-c++ libXi-devel \
     freetype-devel mesa-libGL-devel mesa-libEGL-devel glib2-devel libX11-devel libXrandr-devel gperf \
     fontconfig-devel cabextract ttmkfdir python python-virtualenv python-pip expat-devel \
     rpm-build openssl-devel cmake bzip2-devel libXcursor-devel libXmu-devel mesa-libOSMesa-devel \
-    dbus-devel ncurses-devel
+    dbus-devel ncurses-devel harfbuzz-devel ccache
 ```
 #### On CentOS
 
@@ -107,19 +108,20 @@ sudo yum install curl freeglut-devel libtool gcc-c++ libXi-devel \
     freetype-devel mesa-libGL-devel mesa-libEGL-devel glib2-devel libX11-devel libXrandr-devel gperf \
     fontconfig-devel cabextract ttmkfdir python python-virtualenv python-pip expat-devel \
     rpm-build openssl-devel cmake3 bzip2-devel libXcursor-devel libXmu-devel mesa-libOSMesa-devel \
-    dbus-devel ncurses-devel python34
+    dbus-devel ncurses-devel python34 harfbuzz-devel ccache
 ```
 #### On openSUSE Linux
 ``` sh
 sudo zypper install libX11-devel libexpat-devel libbz2-devel Mesa-libEGL-devel Mesa-libGL-devel cabextract cmake \
     dbus-1-devel fontconfig-devel freetype-devel gcc-c++ git glib2-devel gperf \
     harfbuzz-devel libOSMesa-devel libXcursor-devel libXi-devel libXmu-devel libXrandr-devel libopenssl-devel \
-    python-pip python-virtualenv rpm-build glu-devel
+    python-pip python-virtualenv rpm-build glu-devel ccache
 ```
 #### On Arch Linux
 
 ``` sh
-sudo pacman -S --needed base-devel git python2 python2-virtualenv python2-pip mesa cmake bzip2 libxmu glu pkg-config ttf-fira-sans
+sudo pacman -S --needed base-devel git python2 python2-virtualenv python2-pip mesa cmake bzip2 libxmu glu \
+    pkg-config ttf-fira-sans harfbuzz ccache
 ```
 #### On Gentoo Linux
 
@@ -127,7 +129,8 @@ sudo pacman -S --needed base-devel git python2 python2-virtualenv python2-pip me
 sudo emerge net-misc/curl media-libs/freeglut \
     media-libs/freetype media-libs/mesa dev-util/gperf \
     dev-python/virtualenv dev-python/pip dev-libs/openssl \
-    x11-libs/libXmu media-libs/glu x11-base/xorg-server
+    x11-libs/libXmu media-libs/glu x11-base/xorg-server \
+    media-libs/harfbuzz dev-util/ccache
 ```
 #### On Windows (MSVC)