[llvm-shlib] Fix the i686 MSVC triple check for listing symbols to export in LLVM-C.dll

[mstorsjo]

Summary

https://reviews.llvm.org/D47381 / eb46c95c3e7aeba4d183ca614fe238067eddf97f
changed the triples set up by GetHostTriple.cmake without changing
the corresponding condition in llvm-shlib.

Since then, the 32 bit x86 build of LLVM-C.dll has contained no
exported symbols at all.

[mstorsjo]

llvm/tools/llvm-shlib/CMakeLists.txt

127

I guess one could try to generalize this into matching i*86-*win* or something like that too...

[phosek]

LGTM

llvm/tools/llvm-shlib/CMakeLists.txt

127

That might be better to handle all different variations of the triple.

[mstorsjo]

Generalized the condition to a regex.

llvm/tools/llvm-shlib/CMakeLists.txt

if(LLVM_BUILD_LLVM_C_DYLIB AND MSVC)
   set(LLVM_LINK_COMPONENTS
     ${LLVM_DYLIB_COMPONENTS}
     )
 
   llvm_map_components_to_libnames(LIB_NAMES ${LLVM_DYLIB_COMPONENTS})
   list(REMOVE_DUPLICATES LIB_NAMES)
 
   # The python script needs to know whether symbols are prefixed with underscores or not.
-  if(LLVM_HOST_TRIPLE STREQUAL "i686-pc-win32")
+  if(LLVM_HOST_TRIPLE MATCHES "i?86-.*win.*")
     set(GEN_UNDERSCORE "--underscore")
   else()
     set(GEN_UNDERSCORE "")
   endif()
 
   # Set this name here, not used in multi conf loop,
   # but add script will pick the right one.
   set(LIBSFILE ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/libllvm-c.args)