test-nick-colors: fix and streamline

A recent addition of an N_ELEMENTS macro invocation broke it.

test-nick-colors

@@ -1,12 +1,15 @@
 #!/bin/sh
 # Check whether the terminal colours filtered by our algorithm are legible
 export example=$(
-	tcc "-run -lm" - <<-EOF
+	tcc "-run -lm" - <<-END
 	#include <stddef.h>
 	#include <stdio.h>
 	#include <math.h>
 
-	$(perl -0777 -ne 'print $& if /^.*?\nfilter_color(?s:.*?)^}$/m' degesch.c)
+	#define N_ELEMENTS(a) (sizeof (a) / sizeof ((a)[0]))
+
+	$(perl -0777 -ne 'print $& if /^.*?\nfilter_color(?s:.*?)^}$/m' \
+		"$(dirname "$0")"/degesch.c)
 
 	void main () {
 		size_t len = 0;
@@ -14,7 +17,7 @@ export example=$(
 		for (size_t i = 0; i < len; i++)
 			printf ("<@\\x1b[38;5;%dmIRCuser\\x1b[m> I'm typing!\n", table[i]);
 	}
-	EOF
+	END
 )
 
 # Both should give acceptable results,