[android] Check for Android-specific ARMv7 SIMD generated code.
[android] Check for Android-specific ARMv7 SIMD generated code.

In my testing, it seems that Android default target-attributes/data
layout doesn't seem to match those of iOS in ARMv7 (or Linux or
Windows). This commit introduces target-sdk-name into the checks, and
does a different check depending on the SDK: iOS stays the same; Linux
and Windows use the iOS approach; Android is a different beast.

To check my assumptions, I used the following small C program and
compiled it with Clang from the tree and different targets
(armv7-none-ios, armv7-none-linux-gnueabi, armv7-none-windows-msvc).

```c
typedef float __attribute__((ext_vector_type(3))) float3;
float3 simd_c_args_float3(float3 x) {
  return x;
}
```

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