lkdtm/bugs: Improve warning message for compilers without counted_by support

The current message for telling the user that their compiler does not
support the counted_by attribute in the FAM_BOUNDS test does not make
much sense either grammatically or semantically. Fix it to make it
correct in both aspects.

Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20240321-lkdtm-improve-lack-of-counted_by-msg-v1-1-0fbf7481a29c@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>

Author: nathanchance

drivers/misc/lkdtm/bugs.c

@@ -417,7 +417,7 @@ static void lkdtm_FAM_BOUNDS(void)
 	pr_err("FAIL: survived access of invalid flexible array member index!\n");
 
 	if (!__has_attribute(__counted_by__))
-		pr_warn("This is expected since this %s was built a compiler supporting __counted_by\n",
+		pr_warn("This is expected since this %s was built with a compiler that does not support __counted_by\n",
 			lkdtm_kernel_info);
 	else if (IS_ENABLED(CONFIG_UBSAN_BOUNDS))
 		pr_expected_config(CONFIG_UBSAN_TRAP);