Merge branch 'next'

* next: (51 commits)
  test, adapt fixc_from_fixml_03 test to engine loading, ...
  test, adapt fixc_from_fixml_01 test to engine loading, ...
  test, migrate tests to loading the fix50sp2 engine beforehand
  minor, test, load fix50sp2_cme DSO for cme-settle tests
  hygiene, satisfy both icc and gcc when declaring __fixml_mtypify() inline as forward
  chore, add engdso-private.h to libfixc SOURCES
  chore, add gperfs of all fix version DSOs to dist
  chore, move forward decl out of fixc_get_mty() body so gcc can cope
  chore, remove checking for mxml, it's never been used
  fix, PEBKAC, descend into libltdl subdir if requested so
  hygiene, return after adding absolute path in engdso path fiddler
  test, don't run static fixc_from_fixml tests anymore
  fix, PEBKAC, also weakify fixc_get_mty()
  test, explicitly load the fix50sp2 dso where needed for adder tests
  test, explicitly load fix50sp2 dso for fixc_render_fixml* tests
  test, hygiene, perform fixml2fix tests in order and add (non-working) fix2fixml_03 test
  test, chore, load fix50sp2 for fix2fixml and fixml2fix tests
  minor, actually build fix DSOs with all the built sources
  fix, use versioned includes for the rest of xsl generators
  minor, actually build fix DSOs with fixml-comp-sub
  ...