Change the syntax of the malloc and free commands in lldb-test's
ir-memory-map subcommand to:
<malloc> ::= <label> = malloc <size> <alignment>
<free> ::= free <label>
This should make it easier to read and extend tests in the future, e.g
to test IRMemoryMap::WriteMemory or double-free behavior.
Differential Revision: https://reviews.llvm.org/D47646
llvm-svn: 333930