[X86] Add test cases to fixup-lea.ll for optsize and no size optimization. Add...

[X86] Add test cases to fixup-lea.ll for optsize and no size optimization. Add +/-slow-incdec command lines

We only form inc/dec in FixupLEAs under minsize today, but all other locations in the compiler for inc/dec with optsize.

llvm-svn: 357446