Update conan install wrapper task

gradle.properties

@@ -13,3 +13,5 @@ org.gradle.jvmargs=-Xmx1536m
 # org.gradle.parallel=true
 android.useAndroidX=true
 
+
+org.gradle.configuration-cache=true

pdf2htmlEX/build.gradle

@@ -27,20 +27,47 @@ plugins {
 
 group = rootProject.group
 
-tasks.register('conanInstall') {
-    doFirst {
-        ["armv7", "armv8", "x86", "x86_64"].each { String arch ->
-            exec {
-                commandLine(
-                        "conan", "install", ".",
-                        "--output-folder=build/conan/" + arch,
-                        "--build=missing",
-                        "--profile:host=android-21-" + arch,
-                )
-            }
+abstract class ConanInstallTask extends Exec {
+    @Input
+    abstract Property<String> getArch()
+
+    // Cannot read project.layout.buildDirectory when configuration-cache is enabled
+    @Input
+    abstract Property<String> getArchBuildDirPath()
+
+    @OutputDirectory
+    final Provider<Directory> outputDirectory = archBuildDirPath.map { new File(it) }
+
+    @Override
+    protected void exec() {
+        commandLine(
+                "conan", "install", ".",
+                "--output-folder=" + archBuildDirPath.get(),
+                "--build=missing",
+                "--profile:host=android-21-" + arch.get(),
+        )
+        super.exec()
+    }
+}
+
+["armv8", "armv7", "x86", "x86_64"].each { architecture ->
+    tasks.register('conanInstall-' + architecture, ConanInstallTask) {
+        setArch(architecture)
+        setArchBuildDirPath(new File(project.layout.buildDirectory.get().toString(), 'conan/' + architecture).absolutePath)
+        // Execute at least one conanInstall before running all three others in parallel.
+        // Some issue with conan's local cache
+        // @TODO: isolate and report to conan-client bugtracker
+        if (architecture != "armv8") {
+            dependsOn(tasks.named("conanInstall-armv8"))
         }
     }
 }
+tasks.register("conanInstall") {
+    ["armv7", "armv8", "x86", "x86_64"].each { arch ->
+        dependsOn tasks.named('conanInstall-' + arch)
+    }
+}
+
 tasks.named("preBuild").configure { preBuildTask ->
     preBuildTask.dependsOn(tasks.named("conanInstall"))
 }
@@ -145,7 +172,8 @@ if (System.getenv('SIGNING_KEY')) {
 // Without removing .cxx dir on cleanup, double gradle clean is erroring out.
 // Before removing this workaround, check if "./gradlew assembleDebug; ./gradlew clean; ./gradlew clean" works
 tasks.named("clean") {
+    def dotCxxDir = getLayout().getProjectDirectory().dir(".cxx")
     doFirst {
-        delete getLayout().getProjectDirectory().dir(".cxx")
+        delete dotCxxDir
     }
 }