tests: build error for integration tests for Go 1.14; undefined: __builtin_isinf_sign, undefined: __builtin_isnan

[mewmew]

When running the integration tests of c2go using Go 1.14, a few builtin identifiers are undefined, as illustrated below.

$ go test -tags=integration ./...
--- FAIL: TestIntegrationScripts (8.81s)
    --- FAIL: TestIntegrationScripts/tests/argv.c (5.28s)
        main_test.go:215: Expected 
            Got: # command-line-arguments [command-line-arguments.test]
            build/tests/argv/main_test.go:208:5: undefined: __builtin_isinf_sign
            build/tests/argv/main_test.go:208:73: undefined: __builtin_isnan

Additional information

Clang 9.0.1 was used in the example above.

$ clang -v
clang version 9.0.1 

[kroppt]

I was having this issue. I fixed it by cleaning my local repository of untracked files using git clean -fdx.
Edit: It fixes the issue during normal testing, but indeed this error still occurs for me in integration tests.