Disable native_coverage for libdl

Bug: http://b/116873221
Bug: http://b/124067925

If not,
https://android-review.googlesource.com/c/platform/build/soong/+/848621
breaks blueline_coverage-userdebug target in internal branches with the
following error:
    build/make/core/base_rules.mk:290: error: bionic/libdl:
    MODULE.TARGET.SHARED_LIBRARIES.libdl already defined by
    bionic/libdl.

Test: build blueline_coverage-userdebug in internal branch.

Change-Id: I8fff866ae2e17ce6daa4d8c75c72ceb17e2e73de
diff --git a/libdl/Android.bp b/libdl/Android.bp
index c17e72e..43ddbfe 100644
--- a/libdl/Android.bp
+++ b/libdl/Android.bp
@@ -92,6 +92,7 @@
 
     nocrt: true,
     system_shared_libs: [],
+    native_coverage: false,
 
     // This is placeholder library the actual implementation is (currently)
     // provided by the linker.