Add script to patch Debian's NSIS with i486-capable binaries

.github/workflows/build.yml

@@ -38,6 +38,7 @@ jobs:
       run: |
         sudo apt-get update -q
         sudo apt-get install -qy make nsis nsis-pluginapi mingw-w64-i686-dev cabextract
+        ./build/fix-nsis.sh
 
     - name: Install MinGW toolchain
       run: |

build/fix-nsis.sh

@@ -0,0 +1,35 @@
+#!/bin/bash
+# Fixes NSIS binaries so they run on Pentium/486. Debian's build of NSIS is compiled with MinGW,
+# but they lack any -mcpu flag, so the binaries receive a default of i686. To fix this, we'll
+# download the official Windows build of NSIS and extract its binaries. We only handle stubs though,
+# because we provide our own plugin builds in this repo.
+
+set -e
+
+if [[ $UID != 0 ]]; then
+	echo "This script needs to be run as root (sorry)" >&2
+	exit 1
+fi
+
+if [[ ! -d /usr/share/nsis/Stubs ]]; then
+	echo "NSIS not installed, or Stubs directory is broken" >&2
+	exit 1
+fi
+
+if [[ -d /usr/share/nsis/Stubs_old ]]; then
+	echo "NSIS stubs are already fixed" >&2
+	exit 0
+fi
+
+apt-get install -qy curl p7zip-full
+
+mkdir /tmp/nsis
+cd /tmp/nsis
+
+curl -fSL https://prdownloads.sourceforge.net/nsis/NSIS%203/3.10/nsis-3.10-setup.exe -o nsis.exe
+7z x nsis.exe
+
+mv /usr/share/nsis/Stubs{,_old}
+cp -ra Stubs /usr/share/nsis/Stubs
+
+rm -rf /tmp/nsis