Export the required symbol from DynamicLibraryTests

[chill]

Summary

Running unittests/Support/DynamicLibrary/DynamicLibraryTests fails when LLVM is configured with LLVM_EXPORT_SYMBOLS_FOR_PLUGINS=ON, because the test's version script only contains symbols
extracted from the static libraries, that the test links with, but not those from the main object/executable itself. The patch
explicitly exports the one symbol needed by the test.

[marsupial]

Looks fine as long as you're confident this doesn't interfere when built without LLVM_EXPORT_SYMBOLS_FOR_PLUGINS.

[chill]

In D33490#763597, @marsupial wrote:

Looks fine as long as you're confident this doesn't interfere when built without LLVM_EXPORT_SYMBOLS_FOR_PLUGINS.

Yes, regardless of the state of LLVM_EXPORT_SYMBOLS_FOR_PLUGINS, the build uses the given symbols list instead of
exporting all the symbols or exporting whatever symbols extract_symbols.py decides to export.

[chill]

Requesting a commit, please.

[alekseyshl]

http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-fast/builds/5220 seem to be unhappy about this change.

[rogfer01]

Ok, I will revert this one. @chill will suggest another solution. Sorry for the fuss.

llvm/trunk/unittests/Support/DynamicLibrary/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS Support)
 
+set(LLVM_EXPORTED_SYMBOL_FILE ${CMAKE_CURRENT_SOURCE_DIR}/DynamicLibraryTests.exports)
 add_llvm_unittest(DynamicLibraryTests DynamicLibraryTest.cpp)
 
 export_executable_symbols(DynamicLibraryTests)
 
 add_library(PipSqueak SHARED PipSqueak.cxx)
 
 set_output_directory(PipSqueak
   BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CFG_INTDIR}

llvm/trunk/unittests/Support/DynamicLibrary/DynamicLibraryTests.exports

+TestA