Parameterized tests relying on getWasmEngines() are not getting instantiated

[mpwarres]

Parameterized tests that rely on getWasmEngines() to determine test cases are not actually being instantiated.

I discovered this when I updated googletest to a more recent version that detects uninstantiated parameterized tests, as part of #411.

I believe this is because getWasmEngines() looks for the presence of macro definitions such as PROXY_WASM_HOST_ENGINE_V8 as indication to include that engine in the list to return; however, those preprocessor definitions are only set in the build rules for the libraries for those engines (for example, :v8_lib, and are not visible in the compilation of test/utility.cc.

@martijneken @PiotrSikora FYI