Avoid -target riscv64-linux-androidVanillaIceCream.

clang silently ignores such things rather than reporting them as errors.

With this change, verbose.log.gz says android10000 instead, as expected.

Bug: https://buganizer.corp.google.com/issues/315788463#comment24
Test: treehugger
Change-Id: I0d92b0747912f28065de0d2dc6b4d33d1c2c9857

cc/compiler.go

@@ -479,7 +479,7 @@ func (compiler *baseCompiler) compilerFlags(ctx ModuleContext, flags Flags, deps
 			target += strconv.Itoa(android.FutureApiLevelInt)
 		} else {
 			apiLevel := nativeApiLevelOrPanic(ctx, version)
-			target += apiLevel.String()
+			target += strconv.Itoa(apiLevel.FinalOrFutureInt())
 		}
 	}