Appveyor: Ignore errors from dumpbin parsing rlib

Author: mattico

appveyor.yml

@@ -18,8 +18,8 @@ test_script:
   - cargo test
   - cargo test --release
   - CALL "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat"
-  - dumpbin /disasm target/debug/librustc_builtins.rlib
-  - dumpbin /disasm target/release/librustc_builtins.rlib
+  - dumpbin /disasm target/debug/librustc_builtins.rlib && exit 0
+  - dumpbin /disasm target/release/librustc_builtins.rlib && exit 0
 
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