Add an explicit definition of __ANDROID__=1

Once the aarch64 toolchain is refreshed this will be removed.
Also removed some CFLAG duplications.

Change-Id: I42fd86931263af82042ea696196fb25e948fe9cb
diff --git a/core/combo/TARGET_linux-aarch64.mk b/core/combo/TARGET_linux-aarch64.mk
index bdb3017..1b24435 100644
--- a/core/combo/TARGET_linux-aarch64.mk
+++ b/core/combo/TARGET_linux-aarch64.mk
@@ -77,12 +77,6 @@
 
 TARGET_GLOBAL_CFLAGS += \
 			-fpic -fPIE \
-			$(arch_variant_cflags) \
-			-include $(android_config_h) \
-			-I $(dir $(android_config_h))
-
-TARGET_GLOBAL_CFLAGS += \
-			-fpic -fPIE \
 			-ffunction-sections \
 			-fdata-sections \
 			-funwind-tables \
@@ -94,6 +88,9 @@
 			-include $(android_config_h) \
 			-I $(dir $(android_config_h))
 
+# TODO - remove __ANDROID__ after the next aarch64 toolchain refresh
+TARGET_GLOBAL_CFLAGS += -D__ANDROID__=1
+
 TARGET_GLOBAL_CFLAGS += -fno-strict-volatile-bitfields
 
 # This is to avoid the dreaded warning compiler message: