patch 8.1.2229: cannot color number column above/below cursor differently

Problem:    Cannot color number column above/below cursor differently.
Solution:   Add LineNrAbove and LineNrBelow. (Shaun Brady, closes #624)
diff --git a/src/vim.h b/src/vim.h
index 230f5b3..7b2aa5b 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -1382,6 +1382,8 @@
     , HLF_M	    // "--More--" message
     , HLF_CM	    // Mode (e.g., "-- INSERT --")
     , HLF_N	    // line number for ":number" and ":#" commands
+    , HLF_LNA	    // LineNrAbove
+    , HLF_LNB	    // LineNrBelow
     , HLF_CLN	    // current line number
     , HLF_R	    // return to continue message and yes/no questions
     , HLF_S	    // status lines
@@ -1423,8 +1425,8 @@
 // The HL_FLAGS must be in the same order as the HLF_ enums!
 // When changing this also adjust the default for 'highlight'.
 #define HL_FLAGS {'8', '~', '@', 'd', 'e', 'h', 'i', 'l', 'm', 'M', \
-		  'n', 'N', 'r', 's', 'S', 'c', 't', 'v', 'V', 'w', 'W', \
-		  'f', 'F', 'A', 'C', 'D', 'T', '-', '>', \
+		  'n', 'a', 'b', 'N', 'r', 's', 'S', 'c', 't', 'v', 'V', \
+		  'w', 'W', 'f', 'F', 'A', 'C', 'D', 'T', '-', '>', \
 		  'B', 'P', 'R', 'L', \
 		  '+', '=', 'x', 'X', '*', '#', '_', '!', '.', 'o', 'q', \
 		  'z', 'Z'}