[PATCH] misc BFD flags

[Timothy Wall]

This patch adds the following functionality to bfd and objdump,
primarily for targets using TI COFF:

C_STATLAB:  Define handling for this storage class, which indicates a
load-time (lma) versus run-time (vma) address.
SEC_CLINK: Sections marked with this flag are linked only if
referenced.  Same function as --gc-sections in the linker, but allows
specific sections to be marked.
SEC_BLOCK: Marks a section for blocking, a weaker form of alignment.
Blocked sections must not cross a page boundary, where the page value is
typically either fixed for a given target or the alignment value of the
section.