Merge branch 'rs/strbuf-avoid-redundant-reset'

A redundant strbuf_reset() call in the 'HAVE_GETDELIM' path of
strbuf_getwholeline() has been removed, as getdelim() overwrites the
buffer and the length is updated afterward.

* rs/strbuf-avoid-redundant-reset:
  strbuf: avoid redundant reset in strbuf_getwholeline()