[llvm] [X86][MC] Report error when the instruction length exceeds 15 bytes (PR #83708)

[Fangrui Song via llvm-commits]

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@@ -0,0 +1,25 @@
+# RUN: not llvm-mc -triple x86_64 -show-encoding %s 2>&1 | FileCheck %s
+
+# CHECK: error: the size of instruction must be no longer than 15
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MaskRay wrote:

Test the file/line infomration like 
`[[#@LINE+2]]:34: error:`

https://github.com/llvm/llvm-project/pull/83708