-Wimplicit-fallthrough warning fixes

Comment changes.

bfd/
	* coff-h8300.c: Spell fall through comments consistently.
	* coffgen.c: Likewise.
	* elf32-hppa.c: Likewise.
	* elf32-ppc.c: Likewise.
	* elf32-score.c: Likewise.
	* elf32-score7.c: Likewise.
	* elf64-ppc.c: Likewise.
	* elfxx-aarch64.c: Likewise.
	* elfxx-mips.c: Likewise.
	* cpu-ns32k.c: Add missing fall through comments.
	* elf-m10300.c: Likewise.
	* elf32-arm.c: Likewise.
	* elf32-avr.c: Likewise.
	* elf32-bfin.c: Likewise.
	* elf32-frv.c: Likewise.
	* elf32-i386.c: Likewise.
	* elf32-microblaze.c: Likewise.
	* elf32-nds32.c: Likewise.
	* elf32-ppc.c: Likewise.
	* elf32-rl78.c: Likewise.
	* elf32-rx.c: Likewise.
	* elf32-s390.c: Likewise.
	* elf32-sh.c: Likewise.
	* elf32-tic6x.c: Likewise.
	* elf64-ia64-vms.c: Likewise.
	* elf64-ppc.c: Likewise.
	* elf64-s390.c: Likewise.
	* elf64-x86-64.c: Likewise.
	* elflink.c: Likewise.
	* elfnn-aarch64.c: Likewise.
	* elfnn-ia64.c: Likewise.
	* ieee.c: Likewise.
	* oasys.c: Likewise.
	* pdp11.c: Likewise.
	* srec.c: Likewise.
	* versados.c: Likewise.
opcodes/
	* aarch64-opc.c: Spell fall through comments consistently.
	* i386-dis.c: Likewise.
	* aarch64-dis.c: Add missing fall through comments.
	* aarch64-opc.c: Likewise.
	* arc-dis.c: Likewise.
	* arm-dis.c: Likewise.
	* i386-dis.c: Likewise.
	* m68k-dis.c: Likewise.
	* mep-asm.c: Likewise.
	* ns32k-dis.c: Likewise.
	* sh-dis.c: Likewise.
	* tic4x-dis.c: Likewise.
	* tic6x-dis.c: Likewise.
	* vax-dis.c: Likewise.
binutils/
	* dlltool.c: Spell fall through comments consistently.
	* objcopy.c: Likewise.
	* readelf.c: Likewise.
	* dwarf.c: Add missing fall through comments.
	* elfcomm.c: Likewise.
	* sysinfo.y: Likewise.
	* readelf.c: Likewise.  Also remove extraneous comments.
gas/
	* app.c: Add missing fall through comments.
	* dw2gencfi.c: Likewise.
	* expr.c: Likewise.
	* config/tc-alpha.c: Likewise.
	* config/tc-arc.c: Likewise.
	* config/tc-arm.c: Likewise.
	* config/tc-cr16.c: Likewise.
	* config/tc-crx.c: Likewise.
	* config/tc-dlx.c: Likewise.
	* config/tc-h8300.c: Likewise.
	* config/tc-hppa.c: Likewise.
	* config/tc-i370.c: Likewise.
	* config/tc-i386.c: Likewise.
	* config/tc-i960.c: Likewise.
	* config/tc-ia64.c: Likewise.
	* config/tc-m68hc11.c: Likewise.
	* config/tc-m68k.c: Likewise.
	* config/tc-mep.c: Likewise.
	* config/tc-metag.c: Likewise.
	* config/tc-microblaze.c: Likewise.
	* config/tc-mips.c: Likewise.
	* config/tc-ns32k.c: Likewise.
	* config/tc-rx.c: Likewise.
	* config/tc-score.c: Likewise.
	* config/tc-score7.c: Likewise.
	* config/tc-sh.c: Likewise.
	* config/tc-tic4x.c: Likewise.
	* config/tc-vax.c: Likewise.
	* config/tc-xstormy16.c: Likewise.
	* config/tc-z80.c: Likewise.
	* config/tc-z8k.c: Likewise.
	* config/obj-elf.c: Likewise.
	* config/tc-i386.c: Likewise.
	* depend.c: Spell fall through comments consistently.
	* config/tc-arm.c: Likewise.
	* config/tc-d10v.c: Likewise.
	* config/tc-i960.c: Likewise.
	* config/tc-ia64.c: Likewise.
	* config/tc-m68k.c: Likewise.
	* config/tc-mcore.c: Likewise.
	* config/tc-mep.c: Likewise.
	* config/tc-ns32k.c: Likewise.
	* config/tc-visium.c: Likewise.
	* config/tc-xstormy16.c: Likewise.
	* config/tc-z8k.c: Likewise.
gprof/
	* gprof.c: Add missing fall through comments.
ld/
	* lexsup.c: Spell fall through comments consistently and add
	missing fall through comments.