package/google-breakpad: use PRE_CONFIGURE hooks to copy linux_syscall_support.h

As reported by Bernd [1], using POST_EXTRACT to copy
linux_syscall_support.h break the legal-info target when
google-breakpad package is selected:

/usr/bin/install: cannot stat '/home/bernd/buildroot/buildroot/output/ost/usr/i586-buildroot-linux-uclibc/sysroot/usr/include/linux_syscall_support.h': No such file or directory

This is because linux_syscall_support.h is installed by a dependency
of google-breakpad, and dependencies are only guaranteed to be
available for the configure step of a package. To fix this, we use a
PRE_CONFIGURE hook instead of POST_EXTRACT hook.

[1] http://lists.busybox.net/pipermail/buildroot/2017-May/192844.html



Reported-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>