libtool: fixed parallel build related race

libtool: fixed parallel build related race

While building libtool, the libtool script itself will be regenerated
because OE modifies a dependency[1]. With -jX, this operation (-->
removal, creation of non-x file, 'chmod a+x') can happen at a time when
the script is going to be executed.  This can cause errors like:

| arm-linux-gnueabi-libtool: compile:  ccache arm-linux-gnueabi-gcc ...
| ...
| /bin/sh ./config.status libtool
| ...
| arm-linux-gnueabi-libtool: compile:  ccache arm-linux-gnueabi-gcc ...
| /bin/sh: ./arm-linux-gnueabi-libtool: Permission denied
| make[2]: *** [libltdl/libltdl_libltdl_la-lt__alloc.lo] Error 126

I am not sure whether the custom do_compile_prepend() is still needed.
For now only the issue above will be fixed by executing ./config.status
yet again.

[1] see 648290d5bf4d6ff50d3643bb7ad902dfc23aa702

(From OE-Core rev: e065c11b6066f8c1d37496b58dd853a684cd9136)

Signed-off-by: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>