dart: update to 2.7.1 and fixes x86_64 build failure

packages/dart/build.sh

@@ -1,10 +1,9 @@
 TERMUX_PKG_HOMEPAGE=https://www.dartlang.org/
 TERMUX_PKG_DESCRIPTION="Dart is a general-purpose programming language"
 TERMUX_PKG_LICENSE="BSD"
-TERMUX_PKG_VERSION=2.7.0
+TERMUX_PKG_VERSION=2.7.1
 TERMUX_PKG_REVISION=1
 TERMUX_PKG_BUILD_IN_SRC=true
-TERMUX_PKG_BLACKLISTED_ARCHES="x86_64"
 
 # Dart uses tar and gzip to extract downloaded packages.
 # Busybox-based versions of such utilities cause issues so

packages/dart/fix_x64.patch

@@ -0,0 +1,11 @@
+--- src/sdk/sdk/BUILD.gn	2020-01-25 14:48:17.182600098 +0530
++++ src.mod/sdk/sdk/BUILD.gn	2020-01-25 14:50:26.678937988 +0530
+@@ -329,7 +329,7 @@
+       ignore_patterns = "{}"
+     },
+   ]
+-  if (is_linux) {
++  if (is_linux || is_android) {
+     copy_tree_specs += [
+       {
+         target = "copy_libtensorflowlite_c"