Fix arm64 build

ARCH_ARM_HAVE_NEON only applies to ARMv7 targets, since ARMv8 requires
NEON support.  It may be set anyway on some targets but this shouldn't
be relied on.

Also fix DEFAULT_ARCH not getting set, which currently works anyway but
mostly by accident (ihevcd_init_function_ptr() falls back on the case we
happen to want).

Change-Id: Ided35523f83fdffca313e2bcb71470cdf780fa55
Signed-off-by: Greg Hackmann <ghackmann@google.com>

diff --git a/decoder.arm64.mk b/decoder.arm64.mk
index 8714aaf..316cc26 100644
--- a/decoder.arm64.mk
+++ b/decoder.arm64.mk

@@ -9,7 +9,6 @@
 libhevcd_srcs_c_arm64    +=  decoder/arm/ihevcd_function_selector.c
 libhevcd_srcs_c_arm64    +=  decoder/arm/ihevcd_function_selector_noneon.c
 
-ifeq ($(ARCH_ARM_HAVE_NEON),true)
 libhevcd_srcs_c_arm64    +=  decoder/arm64/ihevcd_function_selector_av8.c
 
 libhevcd_srcs_c_arm64    +=  common/arm/ihevc_intra_pred_filters_neon_intr.c
@@ -84,10 +83,7 @@
 libhevcd_srcs_asm_arm64    +=  decoder/arm64/ihevcd_fmt_conv_420sp_to_420sp.s
 libhevcd_srcs_asm_arm64    +=  decoder/arm64/ihevcd_fmt_conv_420sp_to_rgba8888.s
 
-libhevcd_cflags_arm += -DDEFAULT_ARCH=D_ARCH_ARMV8_GENERIC
-else
-libhevcd_cflags_arm64 += -DDISABLE_NEON -DDEFAULT_ARCH=D_ARCH_ARM_NONEON
-endif
+libhevcd_cflags_arm64 += -DDEFAULT_ARCH=D_ARCH_ARMV8_GENERIC