Major update of the MicroBlaze backend. The new features are:

    1. A delay slot filler that searches for valid instructions
       to fill the delay slot with. Previously NOPs would always
       be inserted into delay slots.
    2. Support for MC based instruction printer added.
    3. Support for MC based machine code generation and ELF
       file generation. ELF file generation does not yet
       completely work as much of the ELF support infrastructure
       is still x86/x86-64 specific.
    4. General clean up of the MBlaze backend code. Much of the
       tablegen code has been cleanup and simplified.

Bug Fixes:
    1. Removed duplicate periods from subtarget feature descriptions.
    2. Many of the instructions had bad machine code information
       in the tablegen files. Much of this has been fixed.

llvm-svn: 116986