This change fabricates linker script commands for the case where there is no linker script SECTIONS to control address assignment. This permits us to have a single Script->assignAddresses() function.
There is a small change in user-visible-behavior with respect to the handling of .tbss SHT_NOBITS, SHF_TLS as the Script->assignAddresses() requires setDot() to be called with monotically increasing addresses. The tls-offset.s test has been updated so that the script and non-script results match. ld.bfd and ld.gold behave similarly to lld with a linker script in that dot is always monotonically increasing.