Merge from gnulib

Merge from gnulib

* doc/misc/texinfo.tex: Update from gnulib.
* lib/getdtablesize.c, lib/getopt.c, lib/signal.in.h, lib/tempname.c:
* lib/tempname.h, m4/dup2.m4, m4/fcntl.m4, m4/getdtablesize.m4:
Update from gnulib, incorporating:
2015-02-20 getdtablesize: port better for Android
2015-02-19 fcntl: Fix cross compiling
2015-02-18 dup2, fcntl: cross-compile better for Android
2015-02-18 getopt: don't crash on memory exhaustion
2015-02-17 tempname: allow compilation with C++ (trivial)
2015-02-17 dup2, fcntl: port to AIX
2015-02-16 getdtablesize, dup2, fcntl: port to Android
2015-02-11 getdtablesize, signal_h: Fix Android build
2015-02-11 maint: various whitespace cleanups in tempname