Remove libLLVM.so and disable some host tools

Bug: http://b/64121881

Remove the libLLVM.so module (and retain libLLVM_android.so).
Simplify the declarations now that there's only one variant.

Tools llvm-ar and LLVMgold.so are disabled instead of having them depend
on libLLVM_android.so.  It is no longer necessary to build them in the
external/llvm project.

Test: aosp_marlin checkbuild with FORCE_BUILD_LLVM_COMPONENTS set and
unset.

Change-Id: Ib9cff7a05eab731a59e4c0d05894931983997ef5

Android.bp

diff --git a/Android.bp b/Android.bp
index f97f88b..cb18605 100644
--- a/Android.bp
+++ b/Android.bp
@@ -201,9 +201,9 @@
     "libLLVMAArch64Disassembler",
 ]
 
-cc_defaults {
+cc_library_shared {
     host_supported: true,
-    name: "libLLVM-defaults",
+    name: "libLLVM_android",
     defaults: [
         "llvm-defaults",
         "force_build_llvm_components",
@@ -301,16 +301,6 @@
     },
 }
 
-cc_library_shared {
-    name: "libLLVM",
-    defaults: ["libLLVM-defaults"],
-}
-
-cc_library_shared {
-    name: "libLLVM_android",
-    defaults: ["libLLVM-defaults"],
-}
-
 subdirs = [
     "soong",
     "lib",