gcc-5: Fix hang with mmusl option on cmdline

gcc-5: Fix hang with mmusl option on cmdline

When using -m32 -mmusl options in this order, gcc hangs
in parsing the options decode_cmdline_options_to_array()
the reason is that we have broken the link when adding
mmusl options, the order of specifying libc was not kept
in order as a result it was unable to contruct the array
correctly and ended in parse hang.

We fix the options to specify the order properly.

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>