[llvm] [AArch64][SVE] Allow basic use of `target("aarch64.svcount")` with +sve (PR #167875)

[Benjamin Maxwell via llvm-commits]

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@@ -10,6 +10,11 @@
 // Properties: guard="sve,sve2p1" streaming_guard="sme,(sve2p1|sme2)" flags="feature-dependent"
 
 void test(void) {
+  // streaming-guard-error at +1 {{SVE vector type 'svcount_t' (aka '__SVCount_t') cannot be used in a non-streaming function}}
+  svcount_t svcount_t_val;
+}
+
+void test_streaming(void) __arm_streaming{
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MacDue wrote:

Anyway, the point is moot, I've updated this PR to allow basic use of svcount in the backend :slightly_smiling_face:. 

https://github.com/llvm/llvm-project/pull/167875