nix: Upgrade to latest gomobile

- Makes a couple of patches redundant;
- Allows specifying min Android SDK level

Signed-off-by: Pedro Pombeiro <pombeirp@users.noreply.github.com>

nix/status-go/default.nix

@@ -31,7 +31,7 @@ let
         "ANDROID_NDK_HOME=${androidPkgs.ndk-bundle}/libexec/android-sdk/ndk-bundle"
         "PATH=${makeBinPath [ openjdk ]}:$PATH"
       ];
-      gomobileExtraFlags = [];
+      gomobileExtraFlags = [ "-androidapi 21" ];
     };
     ios = {
       name = "ios";

nix/status-go/gomobile/default.nix

@@ -11,9 +11,9 @@ let
 
 in buildGoPackage rec {
   pname = "gomobile";
-  version = "20190319-${strings.substring 0 7 rev}";
-  rev = "167ebed0ec6dd457a6b24a4f61db913f0af11f70";
-  sha256 = "0lspdhikhnhbwv8v0q6fs3a0pd9sjnhkpg8z03m2dc5h6f84m38w";
+  version = "20190719-${strings.substring 0 7 rev}";
+  rev = "d2bd2a29d028cb94031e5e81788b19b371d00eb8";
+  sha256 = "1nv6vvhnjr01nx9y06q46ww87dppdwpbqrlsfg1xf2587wxl8xiv";
 
   goPackagePath = "golang.org/x/mobile";
   subPackages = [ "bind" "cmd/gobind" "cmd/gomobile" ];
@@ -24,8 +24,7 @@ in buildGoPackage rec {
   # Ensure XCode and the iPhone SDK are present, instead of failing at the end of the build
   preConfigure = optionalString isDarwin utils.enforceiPhoneSDKAvailable;
 
-  patches = [ ./ndk-search-path.patch ./resolve-nix-android-sdk.patch ]
-    ++ optional isDarwin ./ignore-nullability-error-on-ios.patch;
+  patches = [ ./resolve-nix-android-sdk.patch ];
 
   postPatch = ''
     ${optionalString platform.targetAndroid ''substituteInPlace cmd/gomobile/install.go --replace "\`adb\`" "\`${platform-tools}/bin/adb\`"''}

nix/status-go/gomobile/ignore-nullability-error-on-ios.patch

@@ -1,12 +0,0 @@
-diff --git a/cmd/gomobile/env.go b/cmd/gomobile/env.go
-index dbf9c8c..538cf35 100644
---- a/cmd/gomobile/env.go
-+++ b/cmd/gomobile/env.go
-@@ -138,6 +138,7 @@ func envInit() (err error) {
- 			panic(fmt.Errorf("unknown GOARCH: %q", arch))
- 		}
- 		cflags += " -fembed-bitcode"
-+		cflags += " -Wno-nullability-completeness"
- 		if err != nil {
- 			return err
- 		}

nix/status-go/gomobile/ndk-search-path.patch

@@ -1,20 +0,0 @@
-diff --git a/cmd/gomobile/env.go b/cmd/gomobile/env.go
-index dbf9c8c..a1c835a 100644
---- a/cmd/gomobile/env.go
-+++ b/cmd/gomobile/env.go
-@@ -165,10 +165,13 @@ func ndkRoot() (string, error) {
- 	if androidHome == "" {
- 		return "", errors.New("The Android SDK was not found. Please set ANDROID_HOME to the root of the Android SDK.")
- 	}
--	ndkRoot := filepath.Join(androidHome, "ndk-bundle")
-+	ndkRoot := os.Getenv("ANDROID_NDK_HOME")
-+	if ndkRoot == "" {
-+		ndkRoot = filepath.Join(androidHome, "ndk-bundle")
-+	}
- 	_, err := os.Stat(ndkRoot)
- 	if err != nil {
--		return "", fmt.Errorf("The NDK was not found in $ANDROID_HOME/ndk-bundle (%q). Install the NDK with `sdkmanager 'ndk-bundle'`", ndkRoot)
-+		return "", fmt.Errorf("The NDK was not found in $ANDROID_HOME/ndk-bundle (%q) nor in ANDROID_NDK_HOME. Install the NDK with `sdkmanager 'ndk-bundle'`", ndkRoot)
- 	}
- 	return ndkRoot, nil
- }