texi2pod.pl: Handle @option and @env.

contrib:
	* texi2pod.pl: Handle @option and @env.

gcc:
	* configure.in: Require at least texinfo 4.0.  Check for whether
	Pod::Man is sufficiently recent to regenerate GCC manpages.
	* configure:  Regenerate.
	* Makefile.in (TEXI2POD): Call perl explicitly rather than relying
	on #!.
	(GENERATED_MANPAGES): Define.
	(generated-manpages): New target.  Depend on cpp.1 as well as
	gcov.1.
	(install-man): Depend on $(GENERATED_MANPAGES) (defined by
	configure to generated-manpages or empty) rather than on the
	manpages directly.  Remove execute permission from installed
	gcov.1 as well as cpp.1.
	* cpp.1, gcov.1: Regenerate.

From-SVN: r38668