compilers: Derive CompilerArgs from collections instead of typing
Deriving from typing.MutableSequence does not give us a usable
sequence type on Python 3.5.2.
@@ -386,7 +386,7 @@ class RunResult:
self.stdout = stdout
self.stderr = stderr
-class CompilerArgs(T.MutableSequence[str]):
+class CompilerArgs(collections.abc.MutableSequence):
'''
List-like class that manages a list of compiler arguments. Should be used
while constructing compiler arguments from various sources. Can be
