[lldb] [test] Skip AVX lldb-server test on non-x86 architectures

Skip the AVX-related lldb-server test on non-x86 architectures, as they
do not support AVX.  While technically the test worked on Linux because
the AVX check would simply return false, other platforms do not provide
such a straightforward way of checking for AVX (especially remotely),
and the results of such check may need to be interpreted specially
for the platform in question.

Differential Revision: https://reviews.llvm.org/D97450

lldb/test/API/tools/lldb-server/TestLldbGdbServer.py

@@ -208,6 +208,7 @@ def targetHasAVX(self):
         return " avx " in cpuinfo
 
     @expectedFailureAll(oslist=["windows"]) # no avx for now.
+    @skipIf(archs=no_match(['amd64', 'i386', 'x86_64']))
     @add_test_categories(["llgs"])
     def test_qRegisterInfo_contains_avx_registers(self):
         self.build()