[XCore][Test] XFAIL tests requiring 8-byte stack alignment.

[nigelp-xmos]

Summary

XCore default subtarget does not support 8-byte stack alignment. These failures
can be seen on builder clang-xcore-ubuntu-20-x64 on staging buildbot.

llvm/test/CodeGen/Generic/2008-01-25-dag-combine-mul.ll

 ; RUN: llc < %s
 ; rdar://5707064
 
+; XCore default subtarget does not support 8-byte alignment on stack.
+; XFAIL: xcore
+
 define i32 @f(i16* %pc) {
 entry:
   %acc = alloca i64, align 8    ; <i64*> [#uses=4]
   %tmp97 = load i64, i64* %acc, align 8    ; <i64> [#uses=1]
   %tmp98 = and i64 %tmp97, 4294967295   ; <i64> [#uses=1]
   %tmp99 = load i64, i64* null, align 8    ; <i64> [#uses=1]
   %tmp100 = and i64 %tmp99, 4294967295    ; <i64> [#uses=1]
   %tmp101 = mul i64 %tmp98, %tmp100   ; <i64> [#uses=1]

llvm/test/CodeGen/Generic/inline-asm-mem-clobber.ll

 ; RUN: llc -O2 -no-integrated-as < %s | FileCheck %s
 
+; XCore default subtarget does not support 8-byte alignment on stack.
+; XFAIL: xcore
+
 @G = common global i32 0, align 4
 
 define i32 @foo(i8* %p) nounwind uwtable {
 entry:
   %p.addr = alloca i8*, align 8
   %rv = alloca i32, align 4
   store i8* %p, i8** %p.addr, align 8
   store i32 0, i32* @G, align 4

llvm/test/DebugInfo/Generic/2010-05-03-OriginDIE.ll

 
 ;RUN: llc < %s -o /dev/null
 ;Radar 7937109
 
+;XCore default subtarget does not support 8-byte alignment on stack.
+;XFAIL: xcore
+
 %struct.anon = type { i64, i32, i32, i32, [1 x i32] }
 %struct.gpm_t = type { i32, i8*, [16 x i8], i32, i64, i64, i64, i64, i64, i64, i32, i16, i16, [8 x %struct.gpmr_t] }
 %struct.gpmr_t = type { [48 x i8], [48 x i8], [16 x i8], i64, i64, i64, i64, i16 }
 %struct.gpt_t = type { [8 x i8], i32, i32, i32, i32, i64, i64, i64, i64, [16 x i8], %struct.anon }
 
 @llvm.used = appending global [1 x i8*] [i8* bitcast (void (%struct.gpm_t*, %struct.gpt_t*)* @gpt2gpm to i8*)], section "llvm.metadata" ; <[1 x i8*]*> [#uses=0]
 
 define fastcc void @gpt2gpm(%struct.gpm_t* %gpm, %struct.gpt_t* %gpt) nounwind optsize ssp {