Fix bug in generate_code.pl

The following did fail:

Test 1
foo:SOME_CONSTANT:"string"

Test 2
foo:OTHER_CONSTANT:"string"

due to the first string actually including the second "foo" up to (but no
including) the colon.
diff --git a/tests/scripts/generate_code.pl b/tests/scripts/generate_code.pl
index 81c454c..078e82d 100755
--- a/tests/scripts/generate_code.pl
+++ b/tests/scripts/generate_code.pl
@@ -139,7 +139,7 @@
             $param_defs .= "    char *param$i = params[$i];\n";
             $param_checks .= "    if( verify_string( &param$i ) != 0 ) return( 2 );\n";
             push @dispatch_params, "param$i";
-            $mapping_regex .= ":[^:]+";
+            $mapping_regex .= ":[^:\n]+";
         }
         else
         {