Allow customized relative PYTHONHOME
Summary:
This change allows a hard coded relative PYTHONHOME setting. So that
python can easily be packaged together with lldb.
The change includes:
1. Extend LLDB_RELOCATABLE_PYTHON to all platforms. It defaults to ON
for platforms other than Windows, to keep the behavior compatible.
2. Allows to customize LLDB_PYTHON_HOME. But still defaults to
PYTHON_HOME.
3. LLDB_PYTHON_HOME can be a path relative to liblldb. If it is
relative, we will resolve it before send it to Py_DecodeLocale.
Subscribers: mgorny, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D74727