hack to unbreak check-llvm on win after https://reviews.llvm.org/D97335

fix attempt http://reviews.llvm.org/rGbbdb4c8c9bcef0e didn't work

The problem is that the test tries to look up
llvm_orc_registerJITLoaderGDBWrapper from the llvm-jitlink.exe
executable, but the symbol wasn't exported. Just manually export it
for now. There's a FIXME with a suggestion for a real fix.

tools/llvm-jitlink/CMakeLists.txt

@@ -24,4 +24,16 @@ add_llvm_tool(llvm-jitlink
   llvm-jitlink-macho.cpp
   )
 
+# export_executable_symbols() is a no-op on Windows if neither
+# LLVM_EXPORTED_SYMBOL_FILE nor LLVM_EXPORT_SYMBOLS_FOR_PLUGINS are set, but
+# the jitlink tests need llvm_orc_registerJITLoaderGDBWrapper to be exported
+# from the executable to work.
+# FIXME: Find a better workaround. Maybe this should use LLVM_EXPORTED_SYMBOL_FILE
+# and an .exports file now that the binary has a required export.
+if (WIN32)
+  target_link_options(llvm-jitlink PRIVATE
+    "/export:llvm_orc_registerJITLoaderGDBWrapper"
+    )
+endif()
+
 export_executable_symbols(llvm-jitlink)

utils/gn/secondary/llvm/tools/llvm-jitlink/BUILD.gn

@@ -15,7 +15,9 @@ executable("llvm-jitlink") {
     "llvm-jitlink-macho.cpp",
     "llvm-jitlink.cpp",
   ]
-  if (host_os != "mac" && host_os != "win") {
+  if (host_os == "win") {
+    ldflags = [ "/export:llvm_orc_registerJITLoaderGDBWrapper" ]
+  } else if (host_os != "mac") {
     # Corresponds to export_executable_symbols() in cmake.
     ldflags = [ "-rdynamic" ]
   }