This commit implements serialization of the machine basic block successors. It
uses a YAML flow sequence that contains strings that have the MBB references.
The MBB references in those strings use the same syntax as the MBB machine
operands in the machine instruction strings.
Reviewers: Duncan P. N. Exon Smith
Differential Revision: http://reviews.llvm.org/D10699
llvm-svn: 241093
Alex Lorenz