Merge branch 'jc/strbuf-split'

Merge branch 'jc/strbuf-split'

Arrays of strbuf is often a wrong data structure to use, and
strbuf_split*() family of functions that create them often have
better alternatives.

Update several code paths and replace strbuf_split*().

* jc/strbuf-split:
  trace2: do not use strbuf_split*()
  trace2: trim_trailing_newline followed by trim is a no-op
  sub-process: do not use strbuf_split*()
  environment: do not use strbuf_split*()
  config: do not use strbuf_split()
  notes: do not use strbuf_split*()
  merge-tree: do not use strbuf_split*()
  clean: do not use strbuf_split*() [part 2]
  clean: do not pass the whole structure when it is not necessary
  clean: do not use strbuf_split*() [part 1]
  clean: do not pass strbuf by value
  wt-status: avoid strbuf_split*()