For PR1028:

Add the llvm.stacksave and llvm.stackrestore intrinsics that correspond
to the GCC builtins __builtin_stack_save and __builtin_stack_restore. This
allows the CBE to execute these builtins, and fixes:

   test/CodeGen/CBackend/2007-01-17-StackSaveNRestore.ll
   External/SPEC/CINT2000/176.gcc (CBE)

Patch by Gordon Henriksen.

llvm-svn: 33313