Move default libnativehelper include to mock dir.

Also export the corresponding variable to make.

libnativehelper's include_deprecated contains all of the
headers that are currently used by libraries without
the "nativehelper/" prefix.

The current count of this is this:
      2 ScopedLocalFrame.h
      4 JniInvocation.h
      4 ScopedBytes.h
      5 AsynchronousCloseMonitor.h
      6 toStringArray.h
      7 ScopedStringChars.h
     38 JniConstants.h
     41 ScopedPrimitiveArray.h
     79 ScopedUtfChars.h
     80 UniquePtr.h
    100 ScopedLocalRef.h
    467 JNIHelp.h

Now we can remove each file from the global header include
on a file by file basis.

Bug: 63762847
Test: libs find their headers

Change-Id: Iffc0c1ceb55cc59dc4a70c75d7c0b9ce8397b2cf

cc/config/global.go

@@ -124,7 +124,7 @@ func init() {
 	// This is used by non-NDK modules to get jni.h. export_include_dirs doesn't help
 	// with this, since there is no associated library.
 	pctx.PrefixedExistentPathsForSourcesVariable("CommonNativehelperInclude", "-I",
-		[]string{"libnativehelper/include/nativehelper"})
+		[]string{"libnativehelper/include_deprecated"})
 
 	pctx.SourcePathVariable("ClangDefaultBase", ClangDefaultBase)
 	pctx.VariableFunc("ClangBase", func(config interface{}) (string, error) {

cc/makevars.go

@@ -82,6 +82,16 @@ func makeVarsProvider(ctx android.MakeVarsContext) {
 
 	ctx.Strict("RS_GLOBAL_INCLUDES", "${config.RsGlobalIncludes}")
 
+	nativeHelperIncludeFlags, err := ctx.Eval("${config.CommonNativehelperInclude}")
+	if err != nil {
+		panic(err)
+	}
+	nativeHelperIncludes, nativeHelperSystemIncludes := splitSystemIncludes(ctx, nativeHelperIncludeFlags)
+	if len(nativeHelperSystemIncludes) > 0 {
+		panic("native helper may not have any system includes")
+	}
+	ctx.Strict("JNI_H_INCLUDE", strings.Join(nativeHelperIncludes, " "))
+
 	includeFlags, err := ctx.Eval("${config.CommonGlobalIncludes}")
 	if err != nil {
 		panic(err)