TARGET_SETUP_INCOMING_VARARG_BOUNDS seems to be an unused vestige of the
MPX support.

2019-08-15  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* target.def (setup_incoming_vararg_bounds): Remove.
	* doc/tm.texi.in (TARGET_SETUP_INCOMING_VARARG_BOUNDS): Remove.
	* doc/tm.texi: Regenerate.
	* targhooks.c (default_setup_incoming_vararg_bounds): Delete.
	* targhooks.h (default_setup_incoming_vararg_bounds): Likewise.
	* config/i386/i386.c (ix86_setup_incoming_vararg_bounds): Likewise.
	(TARGET_SETUP_INCOMING_VARARG_BOUNDS): Likewise.

From-SVN: r274539