Upgrade mktemp.c to the current upstream version.

Yet another archaic relic containing bugs that had been fixed years before the
Android project even started...

Bug: 9935113
Change-Id: I3c9d019a216efd609ee568cf8c70bc360f357403
diff --git a/libc/Android.mk b/libc/Android.mk
index a6b464f..f082e30 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -25,7 +25,6 @@
 	stdio/ftell.c \
 	stdio/fvwrite.c \
 	stdio/gets.c \
-	stdio/mktemp.c \
 	stdio/printf.c \
 	stdio/refill.c \
 	stdio/rewind.c \
@@ -270,6 +269,7 @@
     upstream-freebsd/lib/libc/stdio/getc.c \
     upstream-freebsd/lib/libc/stdio/getchar.c \
     upstream-freebsd/lib/libc/stdio/makebuf.c \
+    upstream-freebsd/lib/libc/stdio/mktemp.c \
     upstream-freebsd/lib/libc/stdio/putc.c \
     upstream-freebsd/lib/libc/stdio/putchar.c \
     upstream-freebsd/lib/libc/stdio/puts.c \