Merge from gnulib, improving some licensing wording.

Merge from gnulib, improving some licensing wording.

This clarifies and fixes some licensing issues raised by Glenn Morris
<http://lists.gnu.org/archive/html/bug-gnulib/2011-09/msg00397.html>.
It also merges the latest version of texinfo.tex and has some
MSVC-related changes that don't affect Emacs.
* Makefile.in (GNULIB_TOOL_FLAGS): Avoid msvc-inval, msvc-nothrow,
pathmax, and raise, since these are needed only to address
MSVC-related issues that Emacs doesn't have.
* doc/misc/texinfo.tex, lib/dup2.c, lib/gnulib.mk, lib/signal.in.h:
* lib/sigprocmask.c, lib/stat.c, lib/stdio.in.h, lib/sys_stat.in.h:
* lib/unistd.in.h, m4/dup2.m4, m4/getloadavg.m4, m4/gl-comp.m4:
* m4/include_next.m4, m4/signal_h.m4, m4/signalblocking.m4:
* m4/stdint.m4, m4/stdio_h.m4, m4/sys_stat_h.m4, m4/time_h.m4:
* m4/unistd_h.m4: Merge from gnulib.