[lldb] Allow configuring on Windows with python interpreter within a junction

The current implementation nicely takes into account when the python interpreter is symlinked (or transitively within a symlinked directory). Sadly, `os.path.islink` returns `false` on Windows if instead of Windows symlinks, junctions are used. This has caused me issues after I started using `scoop` as my package manager on Windows, which creates junctions instead of symlinks.
The fix proposed in this patch is to check whether `realpath` returns a different path to `exe`, and if it does, to simply try again with that path.
The code could also be simplified since `sys.executable` is guaranteed to be absolute, and `os.readlink`, which can return a relative path, is no longer used.

Tested on Windows 11 with Python 3.11 as interpreter and Ubuntu 18.04 with Python 3.6

Differential Revision: https://reviews.llvm.org/D141042

diff --git a/lldb/bindings/python/get-python-config.py b/lldb/bindings/python/get-python-config.py
index 32d82a5..6369e32 100755 (executable)
--- a/lldb/bindings/python/get-python-config.py
+++ b/lldb/bindings/python/get-python-config.py
@@ -51,8 +51,10 @@ def main():
                 break
             except ValueError:
                 tried.append(exe)
-                if os.path.islink(exe):
-                    exe = os.path.join(os.path.realpath(os.path.dirname(exe)), os.readlink(exe))
+                # Retry if the executable is symlinked or similar.
+                # This is roughly equal to os.path.islink, except it also works for junctions on Windows.
+                if os.path.realpath(exe) != exe:
+                    exe = os.path.realpath(exe)
                     continue
                 else:
                     print("Could not find a relative path to sys.executable under sys.prefix", file=sys.stderr)