Fix OSS build

Summary:
dsl.cc was added to whisker in aa4d96b6d058dba03eb1a3c68b8fa2c4c23e3e94 but is missing from the corresponding listfile.

X-link: facebook/fbthrift#634

Reviewed By: yoney

Differential Revision: D68237504

Pulled By: vitaut

fbshipit-source-id: f5a0f652d496cba3f27705f5c6a7219749e03f3b

Author: mszabo-wikia

third-party/thrift/src/thrift/compiler/CMakeLists.txt

@@ -168,6 +168,7 @@ add_library(
 
   whisker/detail/string.cc
   whisker/ast.cc
+  whisker/dsl.cc
   whisker/eval_context.cc
   whisker/lexer.cc
   whisker/mstch_compat.cc