remove cruft for libc struct accessor function and broken visibility

remove cruft for libc struct accessor function and broken visibility

these were hacks to work around toolchains that could not properly
optimize PIC accesses based on visibility and would generate GOT
lookups even for hidden data, which broke the old dynamic linker.
since commit f3ddd173806fd5c60b3f034528ca24542aecc5b9 it no longer
matters; the dynamic linker does not assume accessibility of this data
until stage 3.