testsuite: fix dg-* typos

testsuite: fix dg-* typos

I have a handful more of these left but those introduce FAILs, while
these all introduce new PASSes.

libstdc++-v3/ChangeLog:

	* testsuite/std/format/string_neg.cc: Add missing brace for dg-error.

gcc/testsuite/ChangeLog:

	* gcc.dg/analyzer/fd-datagram-socket.c: Fix 'dg-message' spelling.
	* gcc.dg/analyzer/out-of-bounds-zero.c: Fix whitespace in 'dg-additional-options'.
	* gcc.dg/analyzer/strchr-1.c: Fix 'dg-message' whitespace.
	* gnat.dg/sso/q11.adb: Fix 'dg-output' whitespace.