Android builds does not work (with Clang++) on the current master due to missing definition of abort_if_no_jvm().
https://github.com/Microsoft/cpprestsdk/blob/b9dd8eab814892f110853be1098df1b3f77b2ff0/Release/src/pplx/threadpool.cpp#L41
Problem is due to the fact that abort_if_no_jvm() is declared in an anonymous namespace and has no prior declarations before get_jvm_env() uses it.
Solution is to just move the definition of abort_if_no_jvm() above get_jvm_env().