nga-c: remove unused function

FossilOrigin-Name: 4cc9341655b1ccf9bca1d987eec8620604cf1b23ae769ccc46adfaab9e03399b

RELEASE-NOTES

@@ -31,6 +31,7 @@
 
   - supports changes from retro-unu
   - now has separate passes for each step of the assembly process
+  - removed some unused variables
 
 ### Python
 
@@ -44,6 +45,7 @@
 ### nga-c
 
 * reduced redundancy across the various implementations in C
+* removed an unused function
 
 ### nga-python
 

vm/nga-c/retro-unix.c

@@ -407,16 +407,6 @@ void dump_stack() {
   function.
   ---------------------------------------------------------------------*/
 
-int fenced(char *s)
-{
-  int a = strcmp(s, "```");
-  int b = strcmp(s, "~~~");
-  if (a == 0) return 2;
-  if (b == 0) return 1;
-              return 0;
-}
-
-
 /* Check to see if a line is a fence boundary.
    This will check code blocks in all cases, and test blocks
    if tests_enabled is set to a non-zero value. */