-Pstrict.release build flag to disable dev tools

Keep the release build as small as possible, so it is faster.  This also
makes it less important to track all the dev tool projects for security
issues, since they are disabled on release builds.

app/build.gradle

@@ -1,6 +1,12 @@
 apply plugin: 'com.android.application'
-apply plugin: 'checkstyle'
-apply plugin: 'pmd'
+
+// add -Pstrict.release to the gradle command line to enable
+if (project.hasProperty('strict.release')) {
+    println "Running strict release"
+} else {
+    apply from: '../config/checkstyle/checkstyle.gradle'
+    apply from: '../config/pmd/pmd.gradle'
+}
 
 /* gets the version name from the latest Git tag */
 def getVersionName = { ->
@@ -191,40 +197,3 @@ dependencies {
     androidTestImplementation 'androidx.test.uiautomator:uiautomator:2.2.0'
     androidTestImplementation 'androidx.work:work-testing:2.7.1'
 }
-
-checkstyle {
-    toolVersion = '7.2'
-}
-
-task checkstyle(type: Checkstyle) {
-    configFile file("${project.rootDir}/config/checkstyle/checkstyle.xml")
-    source 'src/main/java', 'src/test/java', 'src/androidTest/java'
-    include '**/*.java'
-
-    classpath = files()
-}
-
-pmd {
-    toolVersion = '6.20.0'
-    consoleOutput = true
-}
-
-task pmdMain(type: Pmd) {
-    dependsOn 'assembleDebug'
-    ruleSetFiles = files("${project.rootDir}/config/pmd/rules.xml", "${project.rootDir}/config/pmd/rules-main.xml")
-    ruleSets = [] // otherwise defaults clash with the list in rules.xml
-    source 'src/main/java'
-    include '**/*.java'
-    exclude '**/vendored/**/*.java'
-}
-
-task pmdTest(type: Pmd) {
-    dependsOn 'assembleDebug'
-    ruleSetFiles = files("${project.rootDir}/config/pmd/rules.xml", "${project.rootDir}/config/pmd/rules-test.xml")
-    ruleSets = [] // otherwise defaults clash with the list in rules.xml
-    source 'src/test/java', 'src/androidTest/java'
-    include '**/*.java'
-    exclude '**/vendored/**/*.java'
-}
-
-task pmd(dependsOn: [pmdMain, pmdTest]) {}

config/checkstyle/checkstyle.gradle

@@ -0,0 +1,13 @@
+apply plugin: 'checkstyle'
+
+checkstyle {
+    toolVersion = '7.2'
+}
+
+task checkstyle(type: Checkstyle) {
+    configFile file("${project.rootDir}/config/checkstyle/checkstyle.xml")
+    source 'src/main/java', 'src/test/java', 'src/androidTest/java'
+    include '**/*.java'
+
+    classpath = files()
+}

config/pmd/pmd.gradle

@@ -0,0 +1,26 @@
+apply plugin: 'pmd'
+
+pmd {
+    toolVersion = '6.20.0'
+    consoleOutput = true
+}
+
+task pmdMain(type: Pmd) {
+    dependsOn 'assembleDebug'
+    ruleSetFiles = files("${project.rootDir}/config/pmd/rules.xml", "${project.rootDir}/config/pmd/rules-main.xml")
+    ruleSets = [] // otherwise defaults clash with the list in rules.xml
+    source 'src/main/java'
+    include '**/*.java'
+    exclude '**/vendored/**/*.java'
+}
+
+task pmdTest(type: Pmd) {
+    dependsOn 'assembleDebug'
+    ruleSetFiles = files("${project.rootDir}/config/pmd/rules.xml", "${project.rootDir}/config/pmd/rules-test.xml")
+    ruleSets = [] // otherwise defaults clash with the list in rules.xml
+    source 'src/test/java', 'src/androidTest/java'
+    include '**/*.java'
+    exclude '**/vendored/**/*.java'
+}
+
+task pmd(dependsOn: [pmdMain, pmdTest]) {}