Do not compile ChronoSync support by default

ChronoSync dependency is now made optional
and is kept for testing purposes only.

Also change sig-type to ecdsa-sha256 in nlsr.conf
as ndn-cxx now has strict checking for it.

refs: #5147

Change-Id: I95c9fb844681ebf2c4e7bbb03cc7796a0795de83
diff --git a/nlsr.conf b/nlsr.conf
index 0adf02c..752dc44 100644
--- a/nlsr.conf
+++ b/nlsr.conf
@@ -28,7 +28,7 @@
   state-dir       /var/lib/nlsr        ; path for intermediate state files including sequence directory (Absolute path)
 }
 
-; the neighbor's section contains the configuration for router's neighbors and hellos behavior
+; the neighbors section contains the configuration for router's neighbors and hello protocol behavior
 
 neighbors
 {
@@ -144,7 +144,7 @@
       checker
       {
         type customized
-        sig-type rsa-sha256
+        sig-type ecdsa-sha256
         key-locator
         {
           type name
@@ -172,7 +172,7 @@
       checker
       {
         type customized
-        sig-type rsa-sha256
+        sig-type ecdsa-sha256
         key-locator
         {
           type name
@@ -201,7 +201,7 @@
       checker
       {
         type customized
-        sig-type rsa-sha256
+        sig-type ecdsa-sha256
         key-locator
         {
           type name
@@ -229,7 +229,7 @@
       checker
       {
         type hierarchical
-        sig-type rsa-sha256
+        sig-type ecdsa-sha256
       }
     }
 
@@ -256,7 +256,7 @@
       checker
       {
         type customized
-        sig-type rsa-sha256
+        sig-type ecdsa-sha256
         key-locator
         {
           type name
@@ -277,7 +277,7 @@
       checker
       {
         type hierarchical
-        sig-type rsa-sha256
+        sig-type ecdsa-sha256
       }
     }