Upgrade rust/crates/gdbstub to 0.6.3 am: f15aee5b6c am: 2a1488b2c7 am: f03fa684f6 am: 9d394b410b

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/gdbstub/+/2191020

Change-Id: I153b7581729f88f8acd8d171afb8041fe5013a7a
Signed-off-by: Automerger Merge Worker <[email protected]>