ARM: add AArch32 support and new vcvt instructions

src/flag-definitions.h

Index: src/flag-definitions.h
diff --git a/src/flag-definitions.h b/src/flag-definitions.h
index 1b8a20d7757cbe6595459f0719e65d5331584e4b..7bf2978884ba18e32e5ba9882a733f887c2ea7c3 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -115,6 +115,11 @@ struct MaybeBoolFlag {
 #else
 # define ENABLE_ARMV7_DEFAULT false
 #endif
+#if (defined CAN_USE_ARMV8_INSTRUCTIONS) || !(defined ARM_TEST)
+# define ENABLE_ARMV8_DEFAULT true
+#else
+# define ENABLE_ARMV8_DEFAULT false
+#endif
 #if (defined CAN_USE_VFP32DREGS) || !(defined ARM_TEST)
 # define ENABLE_32DREGS_DEFAULT true
 #else
@@ -365,6 +370,8 @@ DEFINE_bool(enable_vfp3, ENABLE_VFP3_DEFAULT,
             "enable use of VFP3 instructions if available")
 DEFINE_bool(enable_armv7, ENABLE_ARMV7_DEFAULT,
             "enable use of ARMv7 instructions if available (ARM only)")
+DEFINE_bool(enable_armv8, ENABLE_ARMV8_DEFAULT,
+            "enable use of ARMv8 instructions if available (ARM only)")
 DEFINE_bool(enable_neon, ENABLE_NEON_DEFAULT,
             "enable use of NEON instructions if available (ARM only)")
 DEFINE_bool(enable_sudiv, true,