bp2build: do not convert prebuilt cc binaries

These do not have a conversion process yet, do not convert them. Add
more protection against using the wrong conversion for prebuilts in cc.

Test: allowlist project with prebuilt objs/binaries and verify BUILD
      files
Change-Id: Ib26689fa19d6fbb1f5c73ded3b5836165977e987
diff --git a/cc/cc.go b/cc/cc.go
index 0904bd9..b084ecc 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -3453,10 +3453,15 @@
 
 // ConvertWithBp2build converts Module to Bazel for bp2build.
 func (c *Module) ConvertWithBp2build(ctx android.TopDownMutatorContext) {
+	prebuilt := c.IsPrebuilt()
 	if c.Binary() {
-		binaryBp2build(ctx, c, ctx.ModuleType())
+		if !prebuilt {
+			binaryBp2build(ctx, c, ctx.ModuleType())
+		}
 	} else if c.Object() {
-		objectBp2Build(ctx, c)
+		if !prebuilt {
+			objectBp2Build(ctx, c)
+		}
 	} else if c.CcLibrary() {
 		if c.hod == android.HostSupported {
 			return
@@ -3464,12 +3469,15 @@
 
 		static := c.BuildStaticVariant()
 		shared := c.BuildSharedVariant()
-		prebuilt := c.IsPrebuilt()
 
 		if static && shared {
-			libraryBp2Build(ctx, c)
+			if !prebuilt {
+				libraryBp2Build(ctx, c)
+			}
 		} else if !static && !shared {
-			libraryHeadersBp2Build(ctx, c)
+			if !prebuilt {
+				libraryHeadersBp2Build(ctx, c)
+			}
 		} else if static {
 			if prebuilt {
 				prebuiltLibraryStaticBp2Build(ctx, c)