[LLDB] Fix LinuxPTraceDefines_arm64sve.h for AArch64 Linux host

LinuxPTraceDefines_arm64sve.h defines essential macros for manipulating
AArch64 SVE core dump registers. Add guard for aarch64/Linux hosts where
newer versions of ptrace.h or sigcontext.h might already define SVE macros.

Differential Revision: https://reviews.llvm.org/D83541