Additions/linux: support producing builds which work with glibc 2.3.
bugref:9112: tools: update i386 Linux Additions build tool
Add an option - VBOX_WITH_OLD_GLIBC_SUPPORT - for producing Linux Additions
builds which work with glibc 2.3, by not referencing symbols which were
introduced later, including improved versions of APIs supported in glibc 2.3,
by not using GNU_HASH tags and by not using the stack protector.
