This is the final part of adding vxworks tls support.  The vxworks dynamic 
loader has builtin knowledge of the structure of the .tls_vars section, and 
expects it to be statically relocated.  If active dynamic relocations remain for 
that section, things go badly wrong.  Fortunately for each architecture there is 
only one reloc type that is valid in the .tls_vars sections (a 32 or 64 bit 
absolute reloc pointing to the contents of the .tls_data section).

This patch changes each backend's relocate_section routine to detect when we're 
generating a shared vxworks object and processing a .tls_vars input section.  In 
that case we process the expected relocations statically and nullify the dynamic 
relocation by turning it into a NOP reloc.

We have to detect the .tls_vars section by name, there are no particular section 
flags to detect it (vxworks TLS is not like regular TLS).  Nullifying the 
dynamic reloc seemed the simplest approach to take, rather than change the size 
of the dynamic reloc section.

ok?

In case I've not mentioned it, gcc vxwork TLS support is waiting on GCC to go 
back to stage 1 after 4.3 branches.

nathan
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Nathan Sidwell    ::   http://www.codesourcery.com   ::         CodeSourcery