[lld] [lld][ELF] Allow `.data.rel.ro.unlikely` to be RELRO (PR #148920)

[Fangrui Song via llvm-commits]

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+# REQUIRES: x86
+
+# RUN: rm -rf %t && split-file %s %t && cd %t
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux input.s -o a.o
+
+# RUN: ld.lld -z keep-data-section-prefix -T linker-script.lds a.o -o a.out
+# RUN: llvm-readelf -l a.out | FileCheck --check-prefixes=SEG,LS %s
+# RUN: llvm-readelf -S a.out | FileCheck %s --check-prefix=CHECK-LS
+
+# RUN: ld.lld -z keep-data-section-prefix a.o -o b.out
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MaskRay wrote:

Our convention is like `a.o => a`, `b.o => b`. The output file names `out` `out1` `out2` are more common.

https://github.com/llvm/llvm-project/pull/148920