[TSan] Fix incorrect expansion of %deflake lit substitution.

dadc214 introduced a change to
`%deflake` to support a configurable threshold but the patch forgot
to add a trailing space.

compiler-rt/test/tsan/lit.cfg.py

@@ -75,7 +75,7 @@ def build_invocation(compile_flags):
 # Define CHECK-%os to check for OS-dependent output.
 config.substitutions.append( ('CHECK-%os', ("CHECK-" + config.host_os)))
 
-config.substitutions.append( ("%deflake ", os.path.join(os.path.dirname(__file__), "deflake.bash") + " " + config.deflake_threshold))
+config.substitutions.append( ("%deflake ", os.path.join(os.path.dirname(__file__), "deflake.bash") + " " + config.deflake_threshold + " "))
 
 # Default test suffixes.
 config.suffixes = ['.c', '.cpp', '.m', '.mm']