appended clang 3.9

Author: xiazhvera

builder/core/data.py

@@ -509,6 +509,10 @@ class PKG_TOOLS(Enum):
                 'c': "clang-3.9",
                 'cxx': "clang++-3.9",
             },
+            '3.9': {
+                'c': "clang-3.9",
+                'cxx': "clang++-3.9",
+            },
             '6': {
                 'c': "clang-6.0",
                 'cxx': "clang++-6.0",