scripted-diff: Rename nUnconnectingHeaders and fPreferHeaders

-BEGIN VERIFY SCRIPT-
ren() { sed -i "s:\<$1\>:$2:g" $(git grep -l "\<$1\>" ./src ./test); }

ren nUnconnectingHeaders     m_num_unconnecting_headers_msgs
ren fPreferHeaders           m_prefers_headers
ren MAX_UNCONNECTING_HEADERS MAX_NUM_UNCONNECTING_HEADERS_MSGS

-END VERIFY SCRIPT-

test/functional/p2p_sendheaders.py

@@ -546,15 +546,15 @@ class SendHeadersTest(BitcoinTestFramework):
         blocks = []
         # Now we test that if we repeatedly don't send connecting headers, we
         # don't go into an infinite loop trying to get them to connect.
-        MAX_UNCONNECTING_HEADERS = 10
-        for _ in range(MAX_UNCONNECTING_HEADERS + 1):
+        MAX_NUM_UNCONNECTING_HEADERS_MSGS = 10
+        for _ in range(MAX_NUM_UNCONNECTING_HEADERS_MSGS + 1):
             blocks.append(create_block(tip, create_coinbase(height), block_time))
             blocks[-1].solve()
             tip = blocks[-1].sha256
             block_time += 1
             height += 1
 
-        for i in range(1, MAX_UNCONNECTING_HEADERS):
+        for i in range(1, MAX_NUM_UNCONNECTING_HEADERS_MSGS):
             # Send a header that doesn't connect, check that we get a getheaders.
             with p2p_lock:
                 test_node.last_message.pop("getheaders", None)
@@ -568,8 +568,8 @@ class SendHeadersTest(BitcoinTestFramework):
         blocks = blocks[2:]
 
         # Now try to see how many unconnecting headers we can send
-        # before we get disconnected.  Should be 5*MAX_UNCONNECTING_HEADERS
-        for i in range(5 * MAX_UNCONNECTING_HEADERS - 1):
+        # before we get disconnected.  Should be 5*MAX_NUM_UNCONNECTING_HEADERS_MSGS
+        for i in range(5 * MAX_NUM_UNCONNECTING_HEADERS_MSGS - 1):
             # Send a header that doesn't connect, check that we get a getheaders.
             with p2p_lock:
                 test_node.last_message.pop("getheaders", None)