Revert the change that made the PLT readonly. The dynamic linker now
actually uses the fact that the PLT is in a writable segment to avoid
the dependency on the __plt_start and __plt_end symbols.

ok deraadt@

On sparc64, make the PLT read-only. This allows the kernel and ld.so to
load binaries without violating W^X. ld.so will make the PLT temporarily
writable (making it non-executable at the same time) to set up the initial
PLT slots and to do non-lazy relocations and restore permissions afterwards.

Make sure you install an updated ld.so before doing a full build.

ok deraadt@

branches: 1.1.1;
Initial revision