Fixes for memory access violations in the coffdump program.

Fixes for memory access violations in the coffdump program.

	PR binutils/17512
	* coffdump.c (dump_coff_section): Check for a symbol being
	available before printing its name.
	(main): Check the return value from coff_grok.
	* coffgrok.c: Reformat and tidy.
	Add range checks to most functions.
	(coff_grok): Return NULL if the input bfd is not in a COFF
	format.
	* coffgrok.h: Reformat and tidy.
	(struct coff_section): Change the nrelocs field to unsigned.
	* srconv.c (main): Check the return value from coff_grok.

	* coff-i860.c (CALC_ADDEND): Always set an addend value.
	* tekhex.c (getvalue): Add an end pointer parameter.  Use it to
	avoid reading off the end of the buffer.
	(getsym): Likewise.
	(first_phase): Likewise.
	(pass_over): Pass an end pointer to the invoked function.