[lit] Don't enable LSan on darwin for clang 900

[JDevlieghere]

Summary

The latest clang that ships with Xcode (clang 900 or 9.0.0) does not support LSan. This fixes the lit configuration to reflect that.

[fjricci]

Thanks!

llvm/trunk/utils/lit/lit/llvm/config.py

def get_clang_has_lsan(self, clang, triple):
                 "compiler '%s' does not appear to be clang, " % clang_binary +
                 'but test suite is configured to use sanitizers.')
             return False
 
         if re.match(r'.*-linux', triple):
             return True
 
         if re.match(r'^x86_64.*-apple', triple):
-            version_number = int(
-                re.search(r'version ([0-9]+)\.', version_string).group(1))
+            version_regex = re.search(r'version ([0-9]+)\.([0-9]+).([0-9]+)', version_string)
+            major_version_number = int(version_regex.group(1))
+            minor_version_number = int(version_regex.group(3))
             if 'Apple LLVM' in version_string:
-                return version_number >= 9
+                return major_version_number >= 9 and minor_version_number > 0
             else:
-                return version_number >= 5
+                return major_version_number >= 5
 
         return False
 
     def make_itanium_abi_triple(self, triple):
         m = re.match(r'(\w+)-(\w+)-(\w+)', triple)
         if not m:
             self.lit_config.fatal(
                 "Could not turn '%s' into Itanium ABI triple" % triple)