tests/cmd-args: skip testing wrapper scripts if dot is missing

The wrapper scripts use dot. Skip testing these
if dot is missing, because the tests would fail.

We could have sovled this by checking for dot in cmake,
but that way we would skip the whole test if dot is missing.
This way we skip just testing the wrappers.

tests/cmd-args.py

@@ -2,13 +2,19 @@
 
 from os import listdir, access, X_OK
 from subprocess import DEVNULL, PIPE, Popen
+from shutil import which
 
 failed = False
+no_dot = which('dot') is None
 
 def is_exe(f):
     return access(f, X_OK)
 
 for f in filter(lambda x: x.startswith('llvm') and is_exe(x), listdir()):
+    # skip wrapper scripts if 'dot' is missing as they depend on it
+    if no_dot and f in ('llvmdda-dump', 'llvmdg-show'):
+        print(f"{f}\u001b[33m SKIP (needs 'dot')\u001b[0m")
+        continue
     print(f, end='')
     p = Popen(['./' + f, '--version'], stdout=DEVNULL, stderr=PIPE)
     out = p.communicate()[1].decode()