Revert "Switch to NetBSD's strxfrm(3)."

This reverts commit be1d78b0dc899a732c0e9d7515d3023e8004e368

Change-Id: I11a95db474796f3da004f27652b081d5ba4ec9b4
diff --git a/libc/Android.mk b/libc/Android.mk
index 091b066..fd81d7e 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -209,6 +209,7 @@
 	string/strstr.c \
 	string/strtok.c \
 	string/strtotimeval.c \
+	string/strxfrm.c \
 	string/__memcpy_chk.c \
 	string/__memmove_chk.c \
 	string/__memset_chk.c \
@@ -336,7 +337,6 @@
 	regex/regerror.c \
 	regex/regexec.c \
 	regex/regfree.c \
-	upstream-netbsd/libc/string/strxfrm.c \
 
 # The following files are common, but must be compiled
 # with different C flags when building a static C library.
@@ -467,9 +467,6 @@
     -DLOG_ON_HEAP_ERROR \
     -std=gnu99
 
-libc_common_cflags += \
-    -include upstream-netbsd/netbsd-compat.h
-
 # these macro definitions are required to implement the
 # 'timezone' and 'daylight' global variables, as well as
 # properly update the 'tm_gmtoff' field in 'struct tm'.