Make arm32 cpu detection recognize the DragonBoard as arm64.

runtime/vm/cpu_arm.cc

Index: runtime/vm/cpu_arm.cc
diff --git a/runtime/vm/cpu_arm.cc b/runtime/vm/cpu_arm.cc
index c2b7e762d8264fd86bd38004026b0874b5e88519..16f2e182101adac21655952c406178860c9a1ea7 100644
--- a/runtime/vm/cpu_arm.cc
+++ b/runtime/vm/cpu_arm.cc
@@ -167,7 +167,9 @@ void HostCPUFeatures::InitOnce() {
   // Check for ARMv5TE, ARMv6, ARMv7, or aarch64.
   // It can be in either the Processor or Model information fields.
   if (CpuInfo::FieldContains(kCpuInfoProcessor, "aarch64") ||
-      CpuInfo::FieldContains(kCpuInfoModel, "aarch64")) {
+      CpuInfo::FieldContains(kCpuInfoModel, "aarch64") ||
+      CpuInfo::FieldContains(kCpuInfoArchitecture, "8") ||
+      CpuInfo::FieldContains(kCpuInfoArchitecture, "AArch64")) {
     // pretend that this arm64 cpu is really an ARMv7
     arm_version_ = ARMv7;
     is_arm64 = true;