That way, lit's builtin 'env' command can be used for the 'env' bit.
Also it's clearer that way that the 'not' shouldn't cover 'env'
failures.
llvm-svn: 374749
This simplifies various workflows, particularly in debugging/development.
e.g. editors will tend to propagate flags, so you can run
`env CLANGD_FLAGS=-input-mirror-file=/tmp/mirror vim foo.cc` rather than
change the configuration in a persistent way.
(This also gives us a generic lever when we don't know how to customize
the flags in some particular LSP client).
While here, add a test for this and other startup logging, and fix a
couple of direct writes to errs() that should have been logs.
Differential Revision: https://reviews.llvm.org/D65153
llvm-svn: 366991