Clean up <stdlib.h> slightly.

Interestingly, this mostly involves cleaning up our implementation of
various <string.h> functions.

Change-Id: Ifaef49b5cb997134f7bc0cc31bdac844bdb9e089
diff --git a/libc/arch-mips64/mips64.mk b/libc/arch-mips64/mips64.mk
index 6fa7d33..26733cb 100644
--- a/libc/arch-mips64/mips64.mk
+++ b/libc/arch-mips64/mips64.mk
@@ -11,8 +11,6 @@
     bionic/__strcat_chk.cpp \
     bionic/memchr.c \
     bionic/memcmp.c \
-    bionic/memcpy.cpp \
-    bionic/memmove.c \
     bionic/memrchr.c \
     bionic/memset.c \
     bionic/strchr.cpp \
@@ -30,6 +28,8 @@
     upstream-freebsd/lib/libc/string/wmemmove.c \
 
 libc_openbsd_src_files_mips64 += \
+    upstream-openbsd/lib/libc/string/memcpy.c \
+    upstream-openbsd/lib/libc/string/memmove.c \
     upstream-openbsd/lib/libc/string/stpcpy.c \
     upstream-openbsd/lib/libc/string/stpncpy.c \
     upstream-openbsd/lib/libc/string/strcat.c \