aligned_alloc: New module. * lib/stdlib.in.h (aligned_alloc): New declaration. * lib/aligned_alloc.c: New file. * m4/aligned_alloc.m4: New file. * m4/stdlib_h.m4 (gl_STDLIB_H): Test whether aligned_alloc is declared. (gl_STDLIB_H_DEFAULTS): Initialize GNULIB_ALIGNED_ALLOC, HAVE_ALIGNED_ALLOC, REPLACE_ALIGNED_ALLOC. * modules/stdlib (Makefile.am): Substitute GNULIB_ALIGNED_ALLOC, HAVE_ALIGNED_ALLOC, REPLACE_ALIGNED_ALLOC. * modules/aligned_alloc: New file. * tests/test-stdlib-c++.cc (aligned_alloc): Check signature. * doc/posix-functions/aligned_alloc.texi: Mention the new module and the AIX bug.