[android] Include api-level.h for Android and C++ interop.
[android] Include api-level.h for Android and C++ interop.

When the header was used in Android, the usage of __ANDROID_API__ was
not set if the compiler wasn't setting it externally. There was a check
for __ANDROID_API__, which defaulted to zero, and so it didn't pass. The
external function definition was not being done, but in C mode, it
didn't matter because implicit functions are allowed. That's not true in
C++ mode, which fails to compile any code that tries to include this
header.

The solution is including android/api-level.h which will define
__ANDROID_API__ to a very high value if it is not defined already (which
is the default behaviour in the NDK).

sschiau/swift,xwu/swift,nathawes/swift,parkera/swift,parkera/swift,karwa/swift,apple/swift,glessard/swift,JGiola/swift,gribozavr/swift,karwa/swift,rudkx/swift,aschwaighofer/swift,roambotics/swift,glessard/swift,tkremenek/swift,jckarter/swift,parkera/swift,JGiola/swift,tkremenek/swift,glessard/swift,roambotics/swift,hooman/swift,devincoughlin/swift,nathawes/swift,CodaFi/swift,hooman/swift,sschiau/swift,ahoppen/swift,roambotics/swift,CodaFi/swift,devincoughlin/swift,roambotics/swift,tkremenek/swift,lorentey/swift,harlanhaskins/swift,airspeedswift/swift,shahmishal/swift,CodaFi/swift,allevato/swift,jckarter/swift,CodaFi/swift,roambotics/swift,parkera/swift,ahoppen/swift,devincoughlin/swift,glessard/swift,atrick/swift,nathawes/swift,aschwaighofer/swift,gribozavr/swift,allevato/swift,allevato/swift,devincoughlin/swift,harlanhaskins/swift,benlangmuir/swift,jmgc/swift,rudkx/swift,stephentyrone/swift,parkera/swift,nathawes/swift,lorentey/swift,apple/swift,stephentyrone/swift,jckarter/swift,stephentyrone/swift,airspeedswift/swift,parkera/swift,xwu/swift,sschiau/swift,aschwaighofer/swift,devincoughlin/swift,jckarter/swift,gribozavr/swift,benlangmuir/swift,jckarter/swift,xwu/swift,hooman/swift,JGiola/swift,ahoppen/swift,sschiau/swift,tkremenek/swift,hooman/swift,apple/swift,apple/swift,stephentyrone/swift,rudkx/swift,airspeedswift/swift,xwu/swift,jckarter/swift,apple/swift,gribozavr/swift,sschiau/swift,shahmishal/swift,parkera/swift,karwa/swift,JGiola/swift,lorentey/swift,airspeedswift/swift,JGiola/swift,atrick/swift,JGiola/swift,hooman/swift,gregomni/swift,atrick/swift,gregomni/swift,shahmishal/swift,rudkx/swift,sschiau/swift,rudkx/swift,airspeedswift/swift,aschwaighofer/swift,atrick/swift,ahoppen/swift,devincoughlin/swift,glessard/swift,atrick/swift,gribozavr/swift,aschwaighofer/swift,harlanhaskins/swift,shahmishal/swift,atrick/swift,jckarter/swift,jmgc/swift,lorentey/swift,jmgc/swift,karwa/swift,benlangmuir/swift,shahmishal/swift,harlanhaskins/swift,karwa/swift,hooman/swift,devincoughlin/swift,CodaFi/swift,sschiau/swift,stephentyrone/swift,jmgc/swift,lorentey/swift,parkera/swift,gregomni/swift,lorentey/swift,aschwaighofer/swift,ahoppen/swift,devincoughlin/swift,benlangmuir/swift,allevato/swift,rudkx/swift,tkremenek/swift,allevato/swift,allevato/swift,shahmishal/swift,lorentey/swift,airspeedswift/swift,tkremenek/swift,xwu/swift,gregomni/swift,gregomni/swift,benlangmuir/swift,shahmishal/swift,shahmishal/swift,xwu/swift,CodaFi/swift,jmgc/swift,lorentey/swift,gribozavr/swift,apple/swift,gribozavr/swift,roambotics/swift,benlangmuir/swift,karwa/swift,sschiau/swift,ahoppen/swift,aschwaighofer/swift,nathawes/swift,karwa/swift,stephentyrone/swift,glessard/swift,allevato/swift,nathawes/swift,CodaFi/swift,jmgc/swift,harlanhaskins/swift,karwa/swift,harlanhaskins/swift,xwu/swift,stephentyrone/swift,airspeedswift/swift,harlanhaskins/swift,nathawes/swift,hooman/swift,gribozavr/swift,gregomni/swift,jmgc/swift,tkremenek/swift