Abort previous builds in pull requests

This will save precious build time by stopping the build of obsolete
commits.

build/jenkins/pipelines/freeBSD.Jenkinsfile

@@ -19,6 +19,9 @@
 // Due to a compilation bug with SpiderMonkey, the game is only built with the release configuration.
 
 pipeline {
+	// Stop previous build in pull requests, but not in branches
+	options { disableConcurrentBuilds(abortPrevious: env.CHANGE_ID != null) }
+
 	agent {
 		node {
 			label 'FreeBSDAgent'

build/jenkins/pipelines/linux.Jenkinsfile

@@ -18,6 +18,9 @@
 // This pipeline builds the game on Linux (with min and max supported versions of GCC and clang) and runs tests.
 
 pipeline {
+	// Stop previous build in pull requests, but not in branches
+	options { disableConcurrentBuilds(abortPrevious: env.CHANGE_ID != null) }
+
 	agent none
 	stages {
 		stage("Setup") {

build/jenkins/pipelines/macOS.Jenkinsfile

@@ -18,6 +18,9 @@
 // This pipeline builds the game on macOS (which uses the clang-10 compiler) and runs tests.
 
 pipeline {
+	// Stop previous build in pull requests, but not in branches
+	options { disableConcurrentBuilds(abortPrevious: env.CHANGE_ID != null) }
+
 	agent {
 		node {
 			label 'macOSAgent'

build/jenkins/pipelines/windows.Jenkinsfile

@@ -21,6 +21,9 @@ def visualStudioPath = "\"C:\\Program Files (x86)\\Microsoft Visual Studio\\2017
 def buildOptions = "/p:PlatformToolset=v141_xp /p:XPDeprecationWarning=false /t:pyrogenesis /t:AtlasUI /t:test /m:2 /nologo -clp:NoSummary"
 
 pipeline {
+	// Stop previous build in pull requests, but not in branches
+	options { disableConcurrentBuilds(abortPrevious: env.CHANGE_ID != null) }
+
 	agent {
 		node {
 			label 'WindowsAgent'