chore, import latest sxe-compiler.m4 macro package

Signed-off-by: Sebastian Freundt <freundt@fresse.org>
Merge branch 'bld/dist' into next

* bld/dist:
  chore, import latest sxe-compiler.m4 macro package
Merge branch 'next'

* next:
  chore, import latest sxe-compiler.m4 macro package
  (Partial) Revert "ltdl, move SXE_CHECK_LIBLTDL to configure.ac"
  ltdl, workaround libtool LT_CONFIG_H bug
  ltdl, use LTDL_INIT's "recursive" mode
  ltdl, move SXE_CHECK_LIBLTDL to configure.ac
  ltdl, remove unsusd check for ltdl.h