Fix doubled indefinite articles, mostly in comments.

Fix doubled indefinite articles, mostly in comments.

2020-03-14  Jakub Jelinek  <jakub@redhat.com>

	* gimple-fold.c (gimple_fold_builtin_strncpy): Change
	"a an" to "an" in a comment.
	* hsa-common.h (is_a_helper): Likewise.
	* tree-ssa-strlen.c (maybe_diag_stxncpy_trunc): Likewise.
	* config/arc/arc.c (arc600_corereg_hazard): Likewise.
	* config/s390/s390.c (s390_indirect_branch_via_thunk): Likewise.

	* logic.cc (formula::formula): Change "a an" to "an" in a comment.
	* parser.c (cp_debug_parser): Change "a an" to "an" in a string
	literal.