Remove additional prefix for unwind symbols

... when building the static library.

Change-Id: Ibc8892a0b350f351ec4656d4d505bee6dc7f9258
diff --git a/Android.mk b/Android.mk
index 0b94b48..d2e5c06 100644
--- a/Android.mk
+++ b/Android.mk
@@ -253,8 +253,6 @@
 libunwind_build_type := host
 include $(LOCAL_PATH)/Android.build.mk
 libunwind_build_type := target
-# Make sure the static library functions do not interfere with shared version.
-libunwind_cflags += -DUNW_ADDITIONAL_PREFIX
 libunwind_build_target := STATIC_LIBRARY
 include $(LOCAL_PATH)/Android.build.mk
 libunwind_build_type := host
@@ -285,8 +283,7 @@
 
 libunwindbacktrace_cflags += \
     -Wno-old-style-declaration \
-    -fvisibility=hidden \
-    -DUNW_ADDITIONAL_PREFIX \
+    -fvisibility=hidden
 
 libunwind_module := libunwindbacktrace
 libunwind_module_tag := optional