android: Work around NDK ABI incompatibility
android: Work around NDK ABI incompatibility

Workaround for Android <21 making signal() an inline function
around bsd_signal(), and Android >= 21 not having any bsd_signal()
symbol but only signal()

https://bugzilla.gnome.org/show_bug.cgi?id=766235

justinjoy/cerbero,justinjoy/cerbero,nirbheek/cerbero,flexVDI/cerbero,OptoFidelity/cerbero,EricssonResearch/cerbero,GStreamer/cerbero,fluendo/cerbero,fluendo/cerbero,fluendo/cerbero,GStreamer/cerbero,fluendo/cerbero,centricular/cerbero,OptoFidelity/cerbero,shoreflyer/cerbero,shoreflyer/cerbero,multipath-rtp/cerbero,justinjoy/cerbero,shoreflyer/cerbero,GStreamer/cerbero,atsushieno/cerbero,centricular/cerbero,centricular/cerbero,multipath-rtp/cerbero,centricular/cerbero,fluendo/cerbero,flexVDI/cerbero,OptoFidelity/cerbero,atsushieno/cerbero,EricssonResearch/cerbero,GStreamer/cerbero,OptoFidelity/cerbero,EricssonResearch/cerbero,multipath-rtp/cerbero,shoreflyer/cerbero,shoreflyer/cerbero,atsushieno/cerbero,flexVDI/cerbero,multipath-rtp/cerbero,nirbheek/cerbero,nirbheek/cerbero,EricssonResearch/cerbero,flexVDI/cerbero,nirbheek/cerbero,EricssonResearch/cerbero,justinjoy/cerbero,atsushieno/cerbero,multipath-rtp/cerbero,atsushieno/cerbero,centricular/cerbero,flexVDI/cerbero,GStreamer/cerbero