[llvm] Add functionality to llvm-objcopy to remove prefixes (PR #79415)

[Fangrui Song via llvm-commits]

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@@ -0,0 +1,59 @@
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-objcopy --remove-symbol-prefix __pf_ %t %t2
+# RUN: llvm-readelf --symbols %t2 | FileCheck %s
+
+## Show that an empty string is permitted as the argument to
+## --remove-prefix-symbols.
+# RUN: llvm-objcopy --remove-symbol-prefix= %t2 %t3
+# RUN: cmp %t2 %t3
+
+## When both options are present, llvm-objcopy should remove
+## prefixes first, before adding prefixes.
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MaskRay wrote:

Did you forget `--prefix-symbols` as a test?

https://github.com/llvm/llvm-project/pull/79415