Merge "riscv64: typedef struct ucontext {...} ucontext_t." am: 61d435c29a am: b22f1f2df0

Original change: https://android-review.googlesource.com/c/platform/bionic/+/2515775

Change-Id: I466ee3a218001fb4d7da53a21e4169df24c370bc
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>