[librsvg] (14 commits) ...gitlab#191 - Merge branch 'reduce-allocations'

[Federico Mena Quintero <federico src gnome org>]

Summary of changes:

  94bbc26... PropertyBag: don't copy the resulting strings during lookup
  9b11cbb... rsvg_css_parse_opacity(): Remove an allocation
  ff0c578... Factor out an util::utf8_cstr() to borrow a &str from a C c
  242d271... utf8_cstr(): Don't do UTF-8 validation (!)  Libxml2 does it
  073fffd... rsvg_node_chars_append(): Don't copy the string; assume it 
  4852538... rsvg_xml_space_normalize(): Don't copy the incoming string
  a8872d4... rsvg_text_create_layout(): Don't copy the incoming string
  2ce259f... rsvg_length_parse(): Don't copy the incoming string
  10bad9c... rsvg_parse_transform(): Don't copy the incoming string
  adb2e83... rsvg_css_parse_number_optional_number(): Don't copy the inc
  6bff4ea... rsvg_css_parse_number_list(): Don't copy the incoming strin
  5f666a7... rsvg_css_parse_color(): Don't copy the incoming string
  d6cff8b... emit_marker_by_name(): Don't copy the incoming string
  009e8e6... gitlab#191 - Merge branch 'reduce-allocations'