The wrapper script no longer has any purpose on Unix.
Just do a plain symlink to the clang-scan-deps tool.
On Windows, the wrapper executable still is used to inject a
default -target option, if the executable name doesn't contain
a triple.
clang-scan-deps can pick it up automatically from the first argument
now.
For the windows wrapper, keep passing -target, to allow running with
a potentially foreign clang-scan-deps.exe.
If we never set $TARGET, we'd previously miss including $CMD_EXE
in the nested command. (This doesn't happen in actual uses of
the wrapper though, but is included for completeness.)
This matches how the corresponding variable is handled in the C
version of the wrapper.
This picks the architecture by looking for a triple prefix in the
nested command, and passes it as an explicit flag, to let
clang-scan-deps find it.
We also pass -stdlib=libc++, to let it find the libc++ headers
as expected.
Martin Storsjö