From-SVN: r49698
* Makefile.am, acinclude.m4, configure.in: Imported GC 6.1 Alpha 1 and merged local changes. From-SVN: r46283
* include/Makefile.am: New file. It defines include_HEADERS. * Makefile.am (SUBDIRS): New macro, set to include. * configure.in (AC_OUTPUT): Add include/Makefile. From-SVN: r45555