Add simplified installation script

Add a script to download the server and build scrcpy using the
prebuilt server.

BUILD.md

@@ -3,6 +3,37 @@
 Here are the instructions to build _scrcpy_ (client and server).
 
 
+## Simple
+
+If you just want to install the latest release from `master`, follow this
+simplified process.
+
+First, you need to install the required packages:
+
+```bash
+# for Debian/Ubuntu
+sudo apt install ffmpeg libsdl2-2.0-0 adb wget \
+                 gcc git pkg-config meson ninja-build \
+                 libavcodec-dev libavformat-dev libavutil-dev libsdl2-dev
+```
+
+Then clone the repo and execute the installation script
+([source](install_release.sh)):
+
+```bash
+git clone https://github.com/Genymobile/scrcpy
+cd scrcpy
+./install_release.sh
+```
+
+When a new release is out, update the repo and reinstall:
+
+```bash
+git pull
+./install_release.sh
+```
+
+
 ## Branches
 
 ### `master`

README.md

@@ -44,7 +44,10 @@ control it using keyboard and mouse.
  - Windows: [download][direct-win64]
  - macOS: `brew install scrcpy`
 
-Build from sources: [BUILD]
+Build from sources: [BUILD] ([simplified process][BUILD_simple])
+
+[BUILD]: BUILD.md
+[BUILD_simple]: BUILD.md#simple
 
 
 ### Linux
@@ -76,9 +79,8 @@ For Gentoo, an [Ebuild] is available: [`scrcpy/`][ebuild-link].
 [Ebuild]: https://wiki.gentoo.org/wiki/Ebuild
 [ebuild-link]: https://github.com/maggu2810/maggu2810-overlay/tree/master/app-mobilephone/scrcpy
 
-You could also [build the app manually][BUILD] (don't worry, it's not that
-hard).
-
+You could also [build the app manually][BUILD] ([simplified
+process][BUILD_simple]).
 
 
 ### Windows
@@ -763,8 +765,6 @@ A colleague challenged me to find a name as unpronounceable as [gnirehtet].
 
 See [BUILD].
 
-[BUILD]: BUILD.md
-
 
 ## Common issues
 

install_release.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+set -e
+
+BUILDDIR=build-auto
+PREBUILT_SERVER_URL=https://github.com/Genymobile/scrcpy/releases/download/v1.17/scrcpy-server-v1.17
+PREBUILT_SERVER_SHA256=11b5ad2d1bc9b9730fb7254a78efd71a8ff46b1938ff468e47a21b653a1b6725
+
+echo "[scrcpy] Downloading prebuilt server..."
+wget "$PREBUILT_SERVER_URL" -O scrcpy-server
+echo "[scrcpy] Verifying prebuilt server..."
+echo "$PREBUILT_SERVER_SHA256  scrcpy-server" | sha256sum --check
+
+echo "[scrcpy] Building client..."
+rm -rf "$BUILDDIR"
+meson "$BUILDDIR" --buildtype release --strip -Db_lto=true \
+    -Dprebuilt_server=scrcpy-server
+cd "$BUILDDIR"
+ninja
+
+echo "[scrcpy] Installing (sudo)..."
+sudo ninja install