Make the libheap.dylib build into a consistent temp directory so it can be...

Make the libheap.dylib build into a consistent temp directory so it can be reused between lldb invocations. Also add the module name into the directory path that is used to store the target triple specific build of libheap.dylib.

Also added code that will rebuild libheap.dylib if heap_find.cpp is newer that libheap.dylib.

llvm-svn: 155590