Silence spurious warning from lit about missing clang-interpreter

[richard.barton.arm]

Summary

Clang's lit.cfg checks for the presence of a few test binaries, including the clang-interpreter. This binary is only built if building the clang examples, so the check should also only fire if the clang examples are built.

[rengolin]

Makes sense. LGTM. Thanks!

test/lit.cfg

 tool_dirs = os.path.pathsep.join((clang_tools_dir, llvm_tools_dir))
 
 # Regex assertions to reject neighbor hyphens/dots (seen in some tests).
 # For example, don't match 'clang-check-' or '.clang-format'.
 NoPreHyphenDot = r"(?<!(-|\.))"
 NoPostHyphenDot = r"(?!(-|\.))"
 NoPostBar = r"(?!(/|\\))"
 
-for pattern in [r"\bFileCheck\b",
+tool_patterns = [r"\bFileCheck\b",
                  r"\bc-index-test\b",
                  NoPreHyphenDot + r"\bclang-check\b" + NoPostHyphenDot,
                  NoPreHyphenDot + r"\bclang-format\b" + NoPostHyphenDot,
-                NoPreHyphenDot + r"\bclang-interpreter\b" + NoPostHyphenDot,
                  # FIXME: Some clang test uses opt?
                  NoPreHyphenDot + r"\bopt\b" + NoPostBar + NoPostHyphenDot,
                  # Handle these specially as they are strings searched
                  # for during testing.
                  r"\| \bcount\b",
-                r"\| \bnot\b"]:
+                 r"\| \bnot\b"]
+
+if config.clang_examples:
+    tool_patterns.append(NoPreHyphenDot + r"\bclang-interpreter\b" + NoPostHyphenDot)
+
+for pattern in tool_patterns:
     # Extract the tool name from the pattern.  This relies on the tool
     # name being surrounded by \b word match operators.  If the
     # pattern starts with "| ", include it in the string to be
     # substituted.
     tool_match = re.match(r"^(\\)?((\| )?)\W+b([0-9A-Za-z-_]+)\\b\W*$",
                           pattern)
     tool_pipe = tool_match.group(2)
     tool_name = tool_match.group(4)