Just link fixes for b 2763938.

Added wcsxfrm.c and wmemcmp.c to the src files in Android.mk and removed wcsxfrm from wchar.c

Change-Id: Iab9b45cf78c27880d2941c360340a7af6b8964fe
diff --git a/libc/Android.mk b/libc/Android.mk
index b0301ef..4cfa17c 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -229,7 +229,9 @@
 	wchar/wcsstr.c \
 	wchar/wcstok.c \
 	wchar/wcswidth.c \
+	wchar/wcsxfrm.c \
 	wchar/wmemchr.c \
+	wchar/wmemcmp.c \
 	wchar/wmemcpy.c \
 	wchar/wmemmove.c \
 	wchar/wmemset.c \