Downgrade to openjdk8

This is the only supported option for the IDE and crashes otherwise.

See arduino/Arduino#11642

Author: A6GibKm

cc.arduino.arduinoide.json

@@ -5,7 +5,7 @@
     "runtime-version": "20.08",
     "sdk": "org.freedesktop.Sdk",
     "sdk-extensions": [
-        "org.freedesktop.Sdk.Extension.openjdk11"
+        "org.freedesktop.Sdk.Extension.openjdk8"
     ],
     "rename-icon": "arduino",
     "build-options": {
@@ -35,7 +35,7 @@
             "name": "openjdk",
             "buildsystem": "simple",
             "build-commands": [
-                "/usr/lib/sdk/openjdk11/install.sh"
+                "/usr/lib/sdk/openjdk8/install.sh"
             ]
         },
         "shared-modules/libusb/libusb.json",
@@ -60,12 +60,12 @@
             "buildsystem": "simple",
             "build-options": {
                 "env": {
-                    "PATH": "/usr/bin:/usr/lib/sdk/openjdk11/bin",
-                    "JAVA_HOME": "/usr/lib/sdk/openjdk11/jvm/openjdk-11"
+                    "PATH": "/usr/bin:/usr/lib/sdk/openjdk8/bin",
+                    "JAVA_HOME": "/usr/lib/sdk/openjdk8/jvm/java-8-openjdk"
                 }
             },
             "build-commands": [
-                "ant --execdebug build",
+                "./ant/bin/ant --execdebug build",
                 "mkdir -p /app/bin /app/Arduino",
                 "cp -a linux/work/* /app/Arduino",
                 "ln -s /app/Arduino/arduino /app/bin",
@@ -327,6 +327,12 @@
                     "url": "http://downloads.arduino.cc/tools/arduinoOTA-1.3.0-linux_amd64.tar.bz2",
                     "sha256": "aa45ee2441ffc3a122daec5802941d1fa2ac47adf5c5c481b5e0daa4dc259ffa",
                     "dest": "build/linux"
+                },
+                {
+                    "type": "archive",
+                    "url": "https://archive.apache.org/dist/ant/binaries/apache-ant-1.10.11-bin.tar.xz",
+                    "sha256": "baa049855cdecbefa62539555824058e52412e5ebe8f102e1db944cb762e06d9",
+                    "dest": "build/ant"
                 }
             ]
         },