cc: fix version macro for stubs

When a cc module is built against a stub, compiler passes version macro
of the stub lib. Version macro should be numeric, so codenames or
"current" should be mapped to numbers just like how ndkstubgen maps to.

* "current" -> future (10000)
* codenames -> look up api_level.json
* otherwise -> cast to int

Bug: 179329813
Test: m / soong test / manually check the output build.ninja
Change-Id: Ic0e1dd904984e161694a0b77fad5559c06a4462f

cc/library.go

@@ -19,6 +19,7 @@ import (
 	"io"
 	"path/filepath"
 	"regexp"
+	"strconv"
 	"strings"
 	"sync"
 
@@ -1362,8 +1363,11 @@ func (library *libraryDecorator) link(ctx ModuleContext,
 func (library *libraryDecorator) exportVersioningMacroIfNeeded(ctx android.BaseModuleContext) {
 	if library.buildStubs() && library.stubsVersion() != "" && !library.skipAPIDefine {
 		name := versioningMacroName(ctx.Module().(*Module).ImplementationModuleName(ctx))
-		ver := library.stubsVersion()
-		library.reexportFlags("-D" + name + "=" + ver)
+		apiLevel, err := android.ApiLevelFromUser(ctx, library.stubsVersion())
+		if err != nil {
+			ctx.ModuleErrorf("Can't export version macro: %s", err.Error())
+		}
+		library.reexportFlags("-D" + name + "=" + strconv.Itoa(apiLevel.FinalOrPreviewInt()))
 	}
 }