elf: Assume disjointed .rela.dyn and .rela.plt for loader
The patch removes the the ELF_DURING_STARTUP optimization and assume
both .rel.dyn and .rel.plt might not be subsequent. This allows some
code simplification since relocation will be handled independently
where it is done on bootstrap.
At least on x86_64_64, I can not measure any performance implications.
Running 10000 time the command
LD_DEBUG=statistics ./elf/ld.so ./libc.so
And filtering the "total startup time in dynamic loader" result,
the geometric mean is: