objtool-core-2021-02-23

 - Make objtool work for big-endian cross compiles

 - Make stack tracking via stack pointer memory operations match push/pop
   semantics to prepare for architectures w/o PUSH/POP instructions.

 - Add support for analyzing alternatives

 - Improve retpoline detection and handling

 - Improve assembly code coverage on x86

 - Provide support for inlined stack switching