Bug#328183: #328183: no-tls-direct-seg-refs

[Petr Salinger <Petr.Salinger@t-systems.cz>]

> will add a very little extra cost to single thread-specific variable
> accesses, but it shouldn't be noticeable at all.

Well, to be correct, switch -mno-tls-direct-seg-refs
add extra cost to ALL thread-specific variables accesses.

For each thread-specific variable access,
compiler have to reserve scratch register and generate sequence like

	movl %gs:0, %ecx
  	movl %eax, C_SYMBOL_NAME(var@NTPOFF)(%ecx)

instead of one instruction

	movl %eax, %gs:C_SYMBOL_NAME(var@NTPOFF)

Petr