Delete toolchain_library

Test: m && ci
Change-Id: Iab5267e02e3559431d980c70a58b49c2b8b4e6de
diff --git a/cc/cc.go b/cc/cc.go
index 9c35348..31babc2 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -548,8 +548,7 @@
 }
 
 // compiler is the interface for a compiler helper object. Different module decorators may implement
-// this helper differently. For example, compiling a `cc_library` may use a different build
-// statement than building a `toolchain_library`.
+// this helper differently.
 type compiler interface {
 	compilerInit(ctx BaseModuleContext)
 	compilerDeps(ctx DepsContext, deps Deps) Deps
@@ -979,13 +978,6 @@
 	return ""
 }
 
-func (c *Module) ToolchainLibrary() bool {
-	if _, ok := c.linker.(*toolchainLibraryDecorator); ok {
-		return true
-	}
-	return false
-}
-
 func (c *Module) NdkPrebuiltStl() bool {
 	if _, ok := c.linker.(*ndkPrebuiltStlLinker); ok {
 		return true
@@ -2450,10 +2442,6 @@
 		return
 	}
 	if c, ok := to.(*Module); ok {
-		if c.ToolchainLibrary() {
-			// These are always allowed
-			return
-		}
 		if c.NdkPrebuiltStl() {
 			// These are allowed, but they don't set sdk_version
 			return
@@ -3439,10 +3427,6 @@
 	if strings.HasPrefix(ctx.OtherModuleName(c), "libclang_rt") {
 		return nil
 	}
-	// b/154569636: set min_sdk_version correctly for toolchain_libraries
-	if c.ToolchainLibrary() {
-		return nil
-	}
 	// We don't check for prebuilt modules
 	if _, ok := c.linker.(prebuiltLinkerInterface); ok {
 		return nil