Add support for pread64/pwrite64

64-bit pread() and pwrite() is needed for ZipFileRO to be able to read
ludicrously large ZIP files just in case someone is crazy enough to do
it.

Also fix a license header that was apparently mangled.

Change-Id: I6819ef8b36e46b63b40749c95717b1ecf9307033
diff --git a/libc/Android.mk b/libc/Android.mk
index f919e31..59e8e32 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -39,10 +39,12 @@
 	unistd/perror.c \
 	unistd/popen.c \
 	unistd/pread.c \
+	unistd/pread64.c \
 	unistd/pselect.c \
 	unistd/ptsname.c \
 	unistd/ptsname_r.c \
 	unistd/pwrite.c \
+	unistd/pwrite64.c \
 	unistd/raise.c \
 	unistd/reboot.c \
 	unistd/recv.c \