Restore the test for bionic being in an APEX.

This was removed in
https://android-review.googlesource.com/c/platform/build/soong/+/950885
because it appeared that bionic was always in an APEX, but apparently the
ART host tests have bionic outside of an APEX.

Test: art/test/testrunner/run_build_test_target.py -j50 art-linux-bionic-x64
Change-Id: I0b99462e8636da53c87f9250093689aaaf9ea695
diff --git a/cc/library.go b/cc/library.go
index 7889cb1..3053831 100644
--- a/cc/library.go
+++ b/cc/library.go
@@ -957,7 +957,7 @@
 					library.baseInstaller.subDir += "-" + vndkVersion
 				}
 			}
-		} else if len(library.Properties.Stubs.Versions) > 0 {
+		} else if len(library.Properties.Stubs.Versions) > 0 && android.DirectlyInAnyApex(ctx, ctx.ModuleName()) {
 			// Bionic libraries (e.g. libc.so) is installed to the bootstrap subdirectory.
 			// The original path becomes a symlink to the corresponding file in the
 			// runtime APEX.