Description:
------------
Passing to strlen a string with a particular sequence of characters (binary + ascii), strlen returns the wrong number of characters.

The architecture of the host where the problem has happened is x86_64

The php configure is:
./configure --with-openssl --with-zlib --enable-zip --with-pear --with-
mysql --enable-sysvsem --enable-sysvshm --enable-sysvmsg --enable-shmop --enable-pcntl --enable-bcmath --with-apxs
2 --with-gettext --with-gdbm --enable-sockets --enable-mbstring --with-imap-ssl --with-libdir=lib64

Reproduce code:
---------------
$pack_str = pack("N",240); // binary string
$msg = "<msg>"; // ascii string
echo "pack_str: ".strlen($pack_str)."\n"; // OK
echo "msg: ".strlen($msg)."\n"; // OK
$new_str = $pack_str.$msg;
echo "strlen: ".strlen($new_str)."\n"; // KO

Expected result:
----------------
The expected result of last echo is:
strlen: 9

Actual result:
--------------
The actual result of last echo is:
strlen: 6