gdb: make gdbarch predicates return bool

gdb: make gdbarch predicates return bool

gdbarch predicates (functions suffixed _p to check whether a gdbarch
implements a given method) currently return int.  Make them return bool.
There is no expected behavior change.

gdb/ChangeLog:

	* gdbarch.sh: Make generated predicates return bool.
	* gdbarch.c: Re-generate.
	* gdbarch.h: Re-generate.

Change-Id: Ie7ebc1acae62df83da9085ba69327fca551c5a30