Disable concurrent marking/sweeping, and background compilation on ARMv5TE

runtime/vm/flag_list.h

Index: runtime/vm/flag_list.h
diff --git a/runtime/vm/flag_list.h b/runtime/vm/flag_list.h
index cf476ca760f162d23294ddc775c004b5e3263379..278a8ba8f05c6ea8befb7e4fde4e04c680a397fb 100644
--- a/runtime/vm/flag_list.h
+++ b/runtime/vm/flag_list.h
@@ -11,6 +11,14 @@
 #define USING_DBC 0
 #endif
 
+// Disable background compilation by default on armv5te. The relevant
+// implementations are uniprocessors.
+#if defined(TARGET_ARCH_ARM_5TE)
+#define USING_BACKGROUND_COMPILATION false
+#else
+#define USING_BACKGROUND_COMPILATION true
+#endif
+
 // List of all flags in the VM.
 // Flags can be one of three categories:
 // * P roduct flags: Can be set in any of the deployment modes, including in
@@ -29,7 +37,7 @@
 #define FLAG_LIST(P, R, D, C)                                                  \
 P(always_megamorphic_calls, bool, false,                                       \
   "Instance call always as megamorphic.")                                      \
-P(background_compilation, bool, true,                                          \
+P(background_compilation, bool, USING_BACKGROUND_COMPILATION,                  \
   "Run optimizing compilation in background")                                  \
 R(background_compilation_stop_alot, false, bool, false,                        \
   "Stress test system: stop background compiler often.")                       \