[SystemZ] Change -march=systemz to triple and fix mature-mc test

[Kai]

Summary

These two test cases use -march=systemz instead of a triple. In
particular, the used file format is then based on the default host
triple. This leads to different behaviour on different platforms.

The SystemZ implementation uses the integrated assembler for a
long time now. The mature-mc-support test can be fully enabled.

[uweigand]

LGTM, thanks!

llvm/test/CodeGen/SystemZ/mature-mc-support.ll

 ; Test that inline assembly is parsed by the MC layer when MC support is mature
 ; (even when the output is assembly).
-; FIXME: SystemZ doesn't use the integrated assembler by default so we only test
-; that -filetype=obj tries to parse the assembly.
 
-; SKIP: not llc -march=systemz < %s > /dev/null 2> %t1
-; SKIP: FileCheck %s < %t1
+; RUN: not llc -mtriple=s390x-linux-gnu < %s > /dev/null 2> %t1
+; RUN: FileCheck %s < %t1
 
-; RUN: not llc -march=systemz -filetype=obj < %s > /dev/null 2> %t2
+; RUN: not llc -mtriple=s390x-linux-gnu -filetype=obj < %s > /dev/null 2> %t2
 ; RUN: FileCheck %s < %t2
 
 
 module asm " .this_directive_is_very_unlikely_to_exist"
 
 ; CHECK: error: unknown directive

llvm/test/CodeGen/SystemZ/tail-call-mem-intrinsics.ll

-; RUN: llc -march=systemz < %s | FileCheck %s
+; RUN: llc -mtriple=s390x-linux-gnu < %s | FileCheck %s
 
 ; CHECK-LABEL: tail_memcpy:
 ; CHECK: jg memcpy
 define void @tail_memcpy(i8* nocapture %p, i8* nocapture readonly %q, i32 %n) #0 {
 entry:
   tail call void @llvm.memcpy.p0i8.p0i8.i32(i8* %p, i8* %q, i32 %n, i1 false)
   ret void
 }