implement-c.texi (Integers Implementation): Make GCC's promises about signed left shift stronger and clarify the cases when...

2015-11-26  Paolo Bonzini <bonzini@gnu.org>

	* doc/implement-c.texi (Integers Implementation): Make GCC's promises
	about signed left shift stronger and clarify the cases when they're
	broken.

From-SVN: r230931