Fix DebugServer build with GCC4.8

Signed-off-by: Jérôme Duval <jerome.duval@gmail.com>
delete_driver_settings.cpp: Get rid of the weak alias.

As weak aliases are not supported on OS X, this caused problems when
building Haiku on OS X, as this file is also used for the host tools.

Signed-off-by: Axel Dörfler <axeld@pinc-software.de>
rootfs.cpp: Replace undefined behaviour with offsetof.

Signed-off-by: Axel Dörfler <axeld@pinc-software.de>
Fix the agg headers to be proper C++.

Signed-off-by: Axel Dörfler <axeld@pinc-software.de>
Get rid of an error caused by -Werror=unused-function.

Signed-off-by: Axel Dörfler <axeld@pinc-software.de>