objtool/x86: Ignore __x86_indirect_alt_* symbols

Because the __x86_indirect_alt* symbols are just that, objtool will
try and validate them as regular symbols, instead of the alternative
replacements that they are.

This goes sideways for FRAME_POINTER=y builds; which generate a fair
amount of warnings.

Fixes: 9bc0bb50 ("objtool/x86: Rewrite retpoline thunk calls")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/YNCgxwLBiK9wclYJ@hirez.programming.kicks-ass.net

arch/x86/lib/retpoline.S

@@ -58,12 +58,16 @@ SYM_FUNC_START_NOALIGN(__x86_indirect_alt_call_\reg)
 2:	.skip	5-(2b-1b), 0x90
 SYM_FUNC_END(__x86_indirect_alt_call_\reg)
 
+STACK_FRAME_NON_STANDARD(__x86_indirect_alt_call_\reg)
+
 SYM_FUNC_START_NOALIGN(__x86_indirect_alt_jmp_\reg)
 	ANNOTATE_RETPOLINE_SAFE
 1:	jmp	*%\reg
 2:	.skip	5-(2b-1b), 0x90
 SYM_FUNC_END(__x86_indirect_alt_jmp_\reg)
 
+STACK_FRAME_NON_STANDARD(__x86_indirect_alt_jmp_\reg)
+
 .endm
 
 /*