Add ABI checker to CI

It's not currently working because master does not check against ABI.
Only released versions >= 2.4

.github/workflows/linux.build.yml

@@ -20,3 +20,12 @@ jobs:
       - name: Run Linux C++11
         working-directory: ./
         run: ./Scripts/BuildScripts/build_ci_linux.sh
+      - name: ABI Checker Report Generation
+        if: ${{ github.base_ref != 'master' }}
+        run: ./Scripts/BuildScripts/abi_checker.sh 2 $GITHUB_BASE_REF
+      - name: ABI Checker Upload
+        uses: actions/upload-artifact@v2
+        if: ${{ github.base_ref != 'master' }}
+        with:
+          name: abi-checker-reports
+          path: ./build/Debug/lib/compat_reports

Scripts/BuildScripts/abi_checker.sh

@@ -0,0 +1,72 @@
+#!/bin/bash
+
+# Usage:
+#
+# Scripts/BuildScripts/abi_checker.sh 2 branch_name
+#
+# Where 2 is the lver
+# branch_name is optional and is the name of the git branch
+
+cd build/Debug/lib
+mkdir -p AbiDump/$1
+
+if [ -z $2 ]; then
+	branch_name=`git branch --show-current`
+else
+	# Pull Requests can't use git branch, so Github provides it for us
+	branch_name=$2
+fi
+
+#if [[ $branch_name == "master" && $1 != 1 ]]; then
+#	echo "We're in master. Master does not do ABI checks. We're done."
+#	exit
+#fi
+
+if [[ $1 != 1 ]]; then
+	echo "--- Fetching base dumps to compare against ---"
+	wget https://github.com/OGRECave/ogre-next/releases/download/bin-releases/AbiDumps_Ubuntu.18.04.LTS.$2.7z
+
+	echo "--- Extracting base dumps ---"
+	7z x AbiDumps_Ubuntu.18.04.LTS.$2.7z
+fi
+
+sudo apt-get install -y abi-compliance-checker
+
+# Dump the libs
+FILES="*.so*"
+for file in $FILES
+do
+	# Ignore symlinks
+	if ! [[ -L "$file" ]]; then
+		echo "Dumping $file"
+		abi-dumper "$file" -o "AbiDump/$1/$file.dump" -lver $1 &
+	fi
+done
+
+wait
+
+# Generate all reports. We need to gather their exit codes to see if they've failed
+PIDs=()
+for file in $FILES
+do
+	# Ignore symlinks
+	if ! [[ -L "$file" ]]; then
+		echo "Checking AbiDump/1/$file.dump vs AbiDump/$1/$file.dump"
+		abi-compliance-checker -l "$file" -old "AbiDump/1/$file.dump" -new "AbiDump/$1/$file.dump" &
+		PIDs+=($!)
+	fi
+done
+
+EXIT_CODE=0
+for pid in "${PIDs[@]}"
+do
+	echo Waiting for $pid
+    wait "$pid"
+	CODE="$?"
+	if [[ "${CODE}" != "0" ]]; then
+		echo "At least one report failed with exit code => ${CODE}";
+		EXIT_CODE=1;
+	fi
+done
+
+exit $EXIT_CODE