So that the XML isn't one giant line. Which wasn't
a problem for lldb but was for me trying to troubleshoot
it using the logs.
It now looks like:
```
<?xml version="1.0"?>
<target version="1.0">
<architecture>aarch64</architecture>
<feature>
<...>
<reg name="fpcr" .../>
</feature>
</target>
```
Reviewed By: labath
Differential Revision: https://reviews.llvm.org/D134035
ba822e248d