[lldb-vscode] correctly handle multiple sourceMap entries
[lldb-vscode] correctly handle multiple sourceMap entries

Summary:
`lldb-vscode` concatenates a string of sourceMap entries
specified in the config, but fails to put a space between
each entry, which causes the settings command to fail.
This patch adds a space between each mapping.

Patch by Richard Howell

Differential Revision: https://reviews.llvm.org/D67569

git-svn-id: 4c4cc70b1ef44ba2b7963015e681894188cea27e@373016 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/lldb,llvm-mirror/lldb,llvm-mirror/lldb,llvm-mirror/lldb,llvm-mirror/lldb