Determine GC type based on BUILT_KERNEL_VERSION_FILE.

How it works:
1. build/make/core/Makefile generates a txt file with the kernel
   version, which is taken from an explicit BOARD_KERNEL_VERSION value,
   or extracted from the kernel image on the source tree, or extracted
   from the kernel image extracted from the prebuilt boot.img.
   The file is saved at
   $ANDROID_PRODUCT_OUT/obj/PACKAGING/check_vintf_all_intermediates/kernel_version.txt.
2. If PRODUCT_ENABLE_UFFD_GC is "default", meaning the GC type needs to
   be determined by the kernel version, build/make/core/Makefile copies
   kernel_version.txt to
   out/soong/dexpreopt/kernel_version_for_uffd_gc.txt.
3. build/soong/dexpreopt/config.go writes the the UFFD GC flag to
   out/soong/dexpreopt/uffd_gc_flag.txt. The flag is determined by an
   explicit PRODUCT_ENABLE_UFFD_GC value or by contruct_uffd_gc_flag.py,
   which reads kernel_version_for_uffd_gc.txt and determines the flag
   accordingly.
4. dex2oat takes the UFFD GC flag from uffd_gc_flag.txt.
5. post_process_props.py mangles ro.dalvik.vm.enable_uffd_gc based on
   the same logic.

Bug: 321751629
Bug: 319554951
Bug: 318763448
Bug: 319648491
Test: m --no-skip-soong-tests nothing
Test: atest uffd_gc_utils_test
Test: Build with `OVERRIDE_ENABLE_UFFD_GC=default m` for device with no
  UFFD support -
  1. Check the existence of `-Xgc:CMC` in
     out/soong/dexpreopt_arm64/dex_bootjars/android/system/framework/arm64/boot.invocation
     (dex2oat invocation for a boot image)
  2. Check the existence of `-Xgc:CMC` in
     out/soong/.intermediates/packages/apps/Settings/Settings/android_common/dexpreopt/Settings/oat/arm64/package.invocation
     (dex2oat invocation for an app defined in .bp)
  3. Check the existence of `-Xgc:CMC` in
     $ANDROID_PRODUCT_OUT/obj/APPS/Dialer_intermediates/oat/arm64/package.invocation
     (dex2oat invocation for an app defined in .mk)
  4. Check the value of ro.dalvik.vm.enable_uffd_gc in
     $ANDROID_PRODUCT_OUT/product/etc/build.prop
Test: Build with `OVERRIDE_ENABLE_UFFD_GC=default m` for device with
  UFFD support, and do the steps above.
Test: Build with `OVERRIDE_ENABLE_UFFD_GC=true m`, and do the steps
  above.
Test: Build with `OVERRIDE_ENABLE_UFFD_GC=false m`, and do the steps
  above.

Change-Id: I035ad32233e49e2a30ce11f6c7c318a648511ef8
diff --git a/java/dexpreopt_bootjars.go b/java/dexpreopt_bootjars.go
index ec8b4c8..01f60d4 100644
--- a/java/dexpreopt_bootjars.go
+++ b/java/dexpreopt_bootjars.go
@@ -617,7 +617,8 @@
 
 // GenerateSingletonBuildActions generates build rules for the dexpreopt config for Make.
 func (d *dexpreoptBootJars) GenerateSingletonBuildActions(ctx android.SingletonContext) {
-	d.dexpreoptConfigForMake = android.PathForOutput(ctx, getDexpreoptDirName(ctx), "dexpreopt.config")
+	d.dexpreoptConfigForMake =
+		android.PathForOutput(ctx, dexpreopt.GetDexpreoptDirName(ctx), "dexpreopt.config")
 	writeGlobalConfigForMake(ctx, d.dexpreoptConfigForMake)
 }
 
@@ -1066,8 +1067,8 @@
 		cmd.FlagWithArg("--instruction-set-features=", global.InstructionSetFeatures[arch])
 	}
 
-	if global.EnableUffdGc && image.target.Os == android.Android {
-		cmd.Flag("--runtime-arg").Flag("-Xgc:CMC")
+	if image.target.Os == android.Android {
+		cmd.Text("$(cat").Input(globalSoong.UffdGcFlag).Text(")")
 	}
 
 	if global.BootFlags != "" {
@@ -1235,7 +1236,7 @@
 func dumpOatRules(ctx android.ModuleContext, image *bootImageConfig) {
 	var allPhonies android.Paths
 	name := image.name
-	global := dexpreopt.GetGlobalConfig(ctx)
+	globalSoong := dexpreopt.GetGlobalSoongConfig(ctx)
 	for _, image := range image.variants {
 		arch := image.target.Arch.ArchType
 		suffix := arch.String()
@@ -1247,6 +1248,7 @@
 		output := android.PathForOutput(ctx, name+"."+suffix+".oatdump.txt")
 		rule := android.NewRuleBuilder(pctx, ctx)
 		imageLocationsOnHost, _ := image.imageLocations()
+
 		cmd := rule.Command().
 			BuiltTool("oatdump").
 			FlagWithInputList("--runtime-arg -Xbootclasspath:", image.dexPathsDeps.Paths(), ":").
@@ -1254,8 +1256,8 @@
 			FlagWithArg("--image=", strings.Join(imageLocationsOnHost, ":")).Implicits(image.imagesDeps.Paths()).
 			FlagWithOutput("--output=", output).
 			FlagWithArg("--instruction-set=", arch.String())
-		if global.EnableUffdGc && image.target.Os == android.Android {
-			cmd.Flag("--runtime-arg").Flag("-Xgc:CMC")
+		if image.target.Os == android.Android {
+			cmd.Text("$(cat").Input(globalSoong.UffdGcFlag).Text(")")
 		}
 		rule.Build("dump-oat-"+name+"-"+suffix, "dump oat "+name+" "+arch.String())