.file file number checking

.file file number checking

This adds another test for file numbers given in .file directives,
checking that the value can be represented as an unsigned int and that
a memory allocation expression doesn't overflow.  I removed a test
added recently since an earlier test (num < 1) already covers the
(num < 0) case.

	* dwarf2dbg.c: Whitespace fixes.
	(get_filenum): Don't strdup "file".  Adjust error message.
	(dwarf2_directive_filename): Use an unsigned type for "num".
	Catch truncation of file number and overflow of get_filenum
	XRESIZEVEC multiplication.  Delete dead code.