travis, build: switch to NDK 19b, fix gomobile builds (#19171)

* travis, build: switch to NDK 19b, fix gomobile builds

* travis, build: move NDK into its final bundle location

* travis: disable Android build on PRs once again

.travis.yml

@@ -165,10 +165,9 @@ matrix:
         - export GOPATH=$HOME/go
       script:
         # Build the Android archive and upload it to Maven Central and Azure
-        - curl https://dl.google.com/android/repository/android-ndk-r17b-linux-x86_64.zip -o android-ndk-r17b.zip
-        - unzip -q android-ndk-r17b.zip && rm android-ndk-r17b.zip
-        - mv android-ndk-r17b $HOME
-        - export ANDROID_NDK=$HOME/android-ndk-r17b
+        - curl https://dl.google.com/android/repository/android-ndk-r19b-linux-x86_64.zip -o android-ndk-r19b.zip
+        - unzip -q android-ndk-r19b.zip && rm android-ndk-r19b.zip
+        - mv android-ndk-r19b $ANDROID_HOME/ndk-bundle
 
         - mkdir -p $GOPATH/src/github.com/ethereum
         - ln -s `pwd` $GOPATH/src/github.com/ethereum/go-ethereum

build/ci.go

@@ -800,12 +800,8 @@ func doAndroidArchive(cmdline []string) {
 	if os.Getenv("ANDROID_HOME") == "" {
 		log.Fatal("Please ensure ANDROID_HOME points to your Android SDK")
 	}
-	if os.Getenv("ANDROID_NDK") == "" {
-		log.Fatal("Please ensure ANDROID_NDK points to your Android NDK")
-	}
 	// Build the Android archive and Maven resources
 	build.MustRun(goTool("get", "golang.org/x/mobile/cmd/gomobile", "golang.org/x/mobile/cmd/gobind"))
-	build.MustRun(gomobileTool("init", "--ndk", os.Getenv("ANDROID_NDK")))
 	build.MustRun(gomobileTool("bind", "-ldflags", "-s -w", "--target", "android", "--javapkg", "org.ethereum", "-v", "github.com/ethereum/go-ethereum/mobile"))
 
 	if *local {