build: make libunwind a proper project

This allows the build infrastructure to properly detect and build libunwind.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235796 91177308-0d34-0410-b5e6-96231b3b80d8

projects/CMakeLists.txt

@@ -7,7 +7,8 @@ foreach(entry ${entries})
     if((NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/compiler-rt) AND
        (NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/dragonegg) AND
        (NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/libcxx) AND
-       (NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/libcxxabi))
+       (NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/libcxxabi) AND
+       (NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/libunwind))
       add_subdirectory(${entry})
     endif()
   endif()
@@ -23,6 +24,7 @@ if(${LLVM_BUILD_RUNTIME})
     # first.
     add_llvm_external_project(libcxxabi)
     add_llvm_external_project(libcxx)
+    add_llvm_external_project(libunwind)
   endif()
   if(NOT LLVM_BUILD_EXTERNAL_COMPILER_RT)
     add_llvm_external_project(compiler-rt)