[ORC] Restrict JITLoaderPerf LLVM_ALWAYS_EXPORT to Linux (#238241)
PR #237756 added LLVM_ALWAYS_EXPORT to both the Linux and non-Linux stub
definitions in JITLoaderPerf.cpp, breaking static Windows MSVC builds
(https://lab.llvm.org/buildbot/#/builders/flang-x86_64-windows) with
C2375 because LLVM_ALWAYS_EXPORT expands to __declspec(dllexport) while
LLVM_ABI in JITLoaderPerf.h is empty.
Perf JIT support is Linux-only, so drop LLVM_ALWAYS_EXPORT from the
non-Linux stub definitions.
Assisted-by: Gemini