pipe-posix: Make it work in C++ mode. * lib/unistd.in.h: Don't include <io.h>, <fcntl.h> for pipe. (pipe): Use common idiom, not a macro definition. * lib/pipe.c: New file. * m4/pipe.m4: New file. * modules/pipe-posix (Description): Enhance. (Files): Add lib/pipe.c, m4/pipe.m4. (configure.ac): Invoke gl_FUNC_PIPE. * m4/unistd_h.m4 (gl_UNISTD_H_DEFAULTS): Initialize HAVE_PIPE. * modules/unistd (Makefile.am): Substitute HAVE_PIPE. * tests/test-unistd-c++.cc: Check the signature of pipe.

--- a/modules/unistd
+++ b/modules/unistd
@@ -87,6 +87,7 @@
 	      -e 's|@''HAVE_LCHOWN''@|$(HAVE_LCHOWN)|g' \
 	      -e 's|@''HAVE_LINK''@|$(HAVE_LINK)|g' \
 	      -e 's|@''HAVE_LINKAT''@|$(HAVE_LINKAT)|g' \
+	      -e 's|@''HAVE_PIPE''@|$(HAVE_PIPE)|g' \
 	      -e 's|@''HAVE_PIPE2''@|$(HAVE_PIPE2)|g' \
 	      -e 's|@''HAVE_PREAD''@|$(HAVE_PREAD)|g' \
 	      -e 's|@''HAVE_PWRITE''@|$(HAVE_PWRITE)|g' \