Use os_memdup()

Use os_memdup()

This leads to cleaner code overall, and also reduces the size
of the hostapd and wpa_supplicant binaries (in hwsim test build
on x86_64) by about 2.5 and 3.5KiB respectively.

The mechanical conversions all over the code were done with
the following spatch:

    @@
    expression SIZE, SRC;
    expression a;
    @@
    -a = os_malloc(SIZE);
    +a = os_memdup(SRC, SIZE);
    <...
    if (!a) {...}
    ...>
    -os_memcpy(a, SRC, SIZE);

Signed-off-by: Johannes Berg <johannes.berg@intel.com>