MEDIUM: cfgparse: Emit hard error on truncated lines

As announced within the emitted log message this is going to become a hard
error in 2.3. It's 2.3 time now, let's do this.

see 2fd5bdb439da29f15381aeb57c51327ba57674fc
diff --git a/src/cfgparse.c b/src/cfgparse.c
index de82a9f..17db1fc 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -1876,11 +1876,11 @@
 		char *line = thisline;
 
 		if (missing_lf != -1) {
-			ha_warning("parsing [%s:%d]: Stray NUL character at position %d. "
-			           "This will become a hard error in HAProxy 2.3.\n",
-			           file, linenum, (missing_lf + 1));
-			err_code |= ERR_WARN;
+			ha_alert("parsing [%s:%d]: Stray NUL character at position %d.\n",
+			         file, linenum, (missing_lf + 1));
+			err_code |= ERR_ALERT | ERR_FATAL;
 			missing_lf = -1;
+			break;
 		}
 
 		linenum++;
@@ -2086,10 +2086,9 @@
 	}
 
 	if (missing_lf != -1) {
-		ha_warning("parsing [%s:%d]: Missing LF on last line, file might have been truncated at position %d. "
-		           "This will become a hard error in HAProxy 2.3.\n",
-		           file, linenum, (missing_lf + 1));
-		err_code |= ERR_WARN;
+		ha_alert("parsing [%s:%d]: Missing LF on last line, file might have been truncated at position %d.\n",
+		         file, linenum, (missing_lf + 1));
+		err_code |= ERR_ALERT | ERR_FATAL;
 	}
 
 	if (cs && cs->post_section_parser)