Remove libc++ from the musl sysroot am: 9f1ffdd3d9

Original change: https://android-review.googlesource.com/c/platform/external/musl/+/2676536

Change-Id: I9ece5ec7139f92fb84457b735ccb7ab44aee4cdf
Signed-off-by: Automerger Merge Worker <[email protected]>