Remove unnecessary cast in aix-thread.c:ptrace32.

We're casting "addr" into "addr_ptr", but this variable is actually
a parameter with that very same type...

gdb/ChangeLog:

        * aix-thread.c (ptrace32): Remove cast to addr_ptr.
Fix build failure in procfs.c after MERGEPID -> ptid_build conversion.

gdb/ChangeLog:

        * procfs.c (procfs_init_inferior): Fix typo causing the build
        to fail.
Fix syntax error in aix-thread.c:sync_threadlists

This patch fixes a small typo after the BUILD_THREAD -> ptid_build
conversion.

gdb/ChangeLog:

        * aix-thread.c (sync_threadlists): Add missing ')' in call
        to ptid_build.