MINOR: args: add new context for servers

We'll have to support fetch expressions and args on server lines for
"usesrc", "usedst", "sni", etc...
diff --git a/include/types/arg.h b/include/types/arg.h
index cccc565..c38d9d6 100644
--- a/include/types/arg.h
+++ b/include/types/arg.h
@@ -74,6 +74,7 @@
 	ARGC_UIF,      /* unique-id-format */
 	ARGC_RDR,      /* redirect */
 	ARGC_CAP,      /* capture rule */
+	ARGC_SRV,      /* server line */
 };
 
 /* flags used when compiling and executing regex */
diff --git a/src/log.c b/src/log.c
index eac62a0..ffd8f10 100644
--- a/src/log.c
+++ b/src/log.c
@@ -192,6 +192,8 @@
 		return "redirect";
 	case ARGC_CAP:
 		return "capture";
+	case ARGC_SRV:
+		return "server";
 	default:
 		return "undefined(please report this bug)"; /* must never happen */
 	}
diff --git a/src/sample.c b/src/sample.c
index 330f08a..6088869 100644
--- a/src/sample.c
+++ b/src/sample.c
@@ -1125,6 +1125,7 @@
 		case ARGC_RDR: where = "in redirect format string in"; break;
 		case ARGC_CAP: where = "in capture rule in"; break;
 		case ARGC_ACL: ctx = "ACL keyword"; break;
+		case ARGC_SRV: where = "in server directive in"; break;
 		}
 
 		/* set a few default settings */