Remove llndk_headers

Replace llndk_headers with cc_library_headers with
llndk.llndk_headers: true.

Bug: 170784825
Test: m checkbuild
Test: compare out/soong/build.ninja
Test: TestLlndkHeaders
Change-Id: I33b411cd4d474318796c2073375176b82dd8c216
diff --git a/cc/cc.go b/cc/cc.go
index 4d8f4e1..c35f628 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -1121,13 +1121,6 @@
 	return c.VendorProperties.IsLLNDK && !c.VendorProperties.IsVNDKPrivate
 }
 
-func (c *Module) IsLlndkHeaders() bool {
-	if _, ok := c.linker.(*llndkHeadersDecorator); ok {
-		return true
-	}
-	return false
-}
-
 func (c *Module) IsLlndkLibrary() bool {
 	if _, ok := c.linker.(*llndkStubDecorator); ok {
 		return true
@@ -1608,8 +1601,7 @@
 	}
 
 	llndk := c.IsLlndk()
-	_, llndkHeader := c.linker.(*llndkHeadersDecorator)
-	if llndk || llndkHeader || (c.UseVndk() && c.HasNonSystemVariants()) {
+	if llndk || (c.UseVndk() && c.HasNonSystemVariants()) {
 		// .vendor.{version} suffix is added for vendor variant or .product.{version} suffix is
 		// added for product variant only when we have vendor and product variants with core
 		// variant. The suffix is not added for vendor-only or product-only module.