Rip out object splitting
The splitter is an evil Perl script that processes assembler code. Its job can be done better by the linker's --gc-sections flag. GHC passes this flag to the linker whenever -split-sections is passed on the command line.
This is based on @DemiMarie's D2768.
Fixes Trac #11315 (closed) Fixes Trac #9832 (closed) Fixes Trac #8964 (closed) Fixes Trac #8685 (closed) Fixes Trac #8629 (closed)