alpha.c, [...]: Use const0_rtx instead of GEN_INT (0).

alpha.c, [...]: Use const0_rtx instead of GEN_INT (0).

	* config/alpha/alpha.c, config/arm/arm.c, config/c4x/c4x.c,
	config/fr30/fr30.md, config/frv/frv.c, config/frv/frv.md,
	config/h8300/h8300.c, config/ia64/ia64.c, config/ip2k/ip2k.md,
	config/m32r/m32r.md, config/m68hc11/m68hc11.c,
	config/mips/mips.md, config/mmix/mmix.c,
	config/mn10300/mn10300.c, config/mn10300/mn10300.md,
	config/ns32k/ns32k.c, config/pa/pa.md, config/pdp11/pdp11.c,
	config/rs6000/altivec.md, config/s390/s390.c,
	config/s390/s390.h, config/s390/s390.md, config/sh/sh.c,
	config/sh/sh.h, config/sh/sh.md, config/stormy16/stormy16.c:
	Use const0_rtx instead of GEN_INT (0).  Do the same for other
	constants that are readily available.

From-SVN: r77161