Revert to openjdk10 and 18.08

Author: A6GibKm

cc.arduino.arduinoide.json

@@ -1,10 +1,10 @@
 {
     "app-id": "cc.arduino.arduinoide",
     "runtime": "org.freedesktop.Platform",
-    "runtime-version": "19.08",
+    "runtime-version": "18.08",
     "sdk": "org.freedesktop.Sdk",
     "sdk-extensions": [
-        "org.freedesktop.Sdk.Extension.openjdk11"
+        "org.freedesktop.Sdk.Extension.openjdk10"
     ],
     "rename-icon": "arduino",
     "build-options": {
@@ -41,8 +41,8 @@
             "buildsystem": "simple",
             "build-options": {
                 "env": {
-                    "PATH": "/usr/bin:/usr/lib/sdk/openjdk11/jvm/openjdk-11/bin",
-                    "JAVA_HOME": "/usr/lib/sdk/openjdk11/jvm/openjdk-11"
+                    "PATH": "/usr/bin:/usr/lib/sdk/openjdk10/jvm/openjdk-10/bin",
+                    "JAVA_HOME": "/usr/lib/sdk/openjdk10/jvm/openjdk-10"
                 }
             },
             "build-commands": [