runtime(syntax-tests): Retrofit input/c.c. with TEST_SETUP

Also:

- Include a syntax test for Markdown that takes advantage of
  a sourceable setup configuration.
- Update Filelist

closes: #14215

Signed-off-by: Aliaksei Budavei <0x000c70@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/syntax/testdir/dumps/c_00.dump b/runtime/syntax/testdir/dumps/c_00.dump
index 46c42f1..30630c8 100644
--- a/runtime/syntax/testdir/dumps/c_00.dump
+++ b/runtime/syntax/testdir/dumps/c_00.dump
@@ -1,4 +1,5 @@
 >/+0#0000e05#ffffff0|*| |v|i|:|s|e|t| |t|s|=|8+0#e000002&| +0#0000e05&|s|t|s|=|4+0#e000002&| +0#0000e05&|s|w|=|4+0#e000002&| +0#0000e05&|n|o|e|t|:| +0#0000000&@43
+| +0#0000e05&|*| |T|E|S|T|_|S|E|T|U|P| |l|e|t| |g|:|c|_|c|o|m@1|e|n|t|_|s|t|r|i|n|g|s| |=| |1+0#e000002&| +0#0000000&@33
 | +0#0000e05&|*| +0#0000000&@72
 | +0#0000e05&|*| |V|I|M| |-| |V|i| |I|M|p|r|o|v|e|d| @3|b|y| |B|r|a|m| |M|o@1|l|e|n|a@1|r| +0#0000000&@33
 | +0#0000e05&|*| +0#0000000&@72
@@ -16,5 +17,4 @@
 @32|/+0#0000e05&@1| |c|y|g|w|i|n|_|c|o|n|v|_|p|a|t|h|(|)| +0#0000000&@21
 |#+0#e000e06&| |i|n|c|l|u|d|e| |<+0#e000002&|l|i|m|i|t|s|.|h|>| +0#0000000&@54
 |#+0#e000e06&|e|n|d|i|f| +0#0000000&@68
-@75
 @57|1|,|1| @10|T|o|p|