[CMake] Check runtimes subdir when looking for libcxx and libuwind

[phosek]

Summary

The runtimes subdir is the new location for runtimes, we should
include it when looking for libcxx and libunwind headers.

[beanz]

LGTM!

[phosek]

The original version caused a build breakage because LIBCXXABI_LIBCXX_SRC_DIR was used both as a string and a list in different contexts. This is a reland of the same change which addresses that issue, please take a look.

libcxxabi/trunk/CMakeLists.txt

 option(LIBCXXABI_ENABLE_SHARED "Build libc++abi as a shared library." ON)
 option(LIBCXXABI_ENABLE_STATIC "Build libc++abi as a static library." ON)
 
 if (NOT LIBCXXABI_ENABLE_SHARED AND NOT LIBCXXABI_ENABLE_STATIC)
   message(FATAL_ERROR "libc++abi must be built as either a shared or static library.")
 endif()
 
 if (LLVM_EXTERNAL_LIBCXX_SOURCE_DIR)
-  set(LIBCXXABI_LIBCXX_SRC_DIR ${LLVM_EXTERNAL_LIBCXX_SOURCE_DIR})
+  set(LIBCXXABI_LIBCXX_SRC_DIRS ${LLVM_EXTERNAL_LIBCXX_SOURCE_DIR})
 else()
-  set(LIBCXXABI_LIBCXX_SRC_DIR ${LLVM_MAIN_SRC_DIR}/projects/libcxx)
+  set(LIBCXXABI_LIBCXX_SRC_DIRS
+    "${LLVM_MAIN_SRC_DIR}/projects/libcxx"
+    "${LLVM_MAIN_SRC_DIR}/runtimes/libcxx"
+    )
 endif()
 
+set(LIBCXXABI_LIBCXX_INCLUDE_DIRS "")
+foreach(dir ${LIBCXXABI_LIBCXX_SRC_DIRS})
+  list(APPEND LIBCXXABI_LIBCXX_INCLUDE_DIRS "${dir}/include")
+endforeach()
+
 find_path(
   LIBCXXABI_LIBCXX_INCLUDES
   vector
   PATHS ${LIBCXXABI_LIBCXX_INCLUDES}
         ${LIBCXXABI_LIBCXX_PATH}/include
         ${CMAKE_BINARY_DIR}/${LIBCXXABI_LIBCXX_INCLUDES}
-        ${LIBCXXABI_LIBCXX_SRC_DIR}/include
+        ${LIBCXXABI_LIBCXX_INCLUDE_DIRS}
         ${LLVM_INCLUDE_DIR}/c++/v1
   )
 
 set(LIBCXXABI_LIBCXX_INCLUDES "${LIBCXXABI_LIBCXX_INCLUDES}" CACHE PATH
     "Specify path to libc++ includes." FORCE)
 
 find_path(
   LIBCXXABI_LIBCXX_PATH
   test/libcxx/__init__.py
   PATHS ${LIBCXXABI_LIBCXX_PATH}
         ${LIBCXXABI_LIBCXX_INCLUDES}/../
-        ${LIBCXXABI_LIBCXX_SRC_DIR}
+        ${LIBCXXABI_LIBCXX_SRC_DIRS}
   NO_DEFAULT_PATH
   )
 
 if (LIBCXXABI_LIBCXX_PATH STREQUAL "LIBCXXABI_LIBCXX_PATH-NOTFOUND")
   message(WARNING "LIBCXXABI_LIBCXX_PATH was not specified and couldn't be infered.")
   set(LIBCXXABI_LIBCXX_PATH "")
 endif()
 

 if (LIBCXXABI_USE_LLVM_UNWINDER OR LLVM_NATIVE_ARCH MATCHES ARM)
   find_path(
     LIBCXXABI_LIBUNWIND_INCLUDES_INTERNAL
     libunwind.h
     PATHS ${LIBCXXABI_LIBUNWIND_INCLUDES}
           ${LIBCXXABI_LIBUNWIND_PATH}/include
           ${CMAKE_BINARY_DIR}/${LIBCXXABI_LIBUNWIND_INCLUDES}
           ${LLVM_MAIN_SRC_DIR}/projects/libunwind/include
+          ${LLVM_MAIN_SRC_DIR}/runtimes/libunwind/include
     NO_DEFAULT_PATH
   )
 
   find_path(
     LIBCXXABI_LIBUNWIND_SOURCES
     libunwind_ext.h
     PATHS ${LIBCXXABI_LIBUNWIND_PATH}/src/
           ${LIBCXXABI_LIBUNWIND_INCLUDES}/../src/
           ${LLVM_MAIN_SRC_DIR}/projects/libunwind/src/
+          ${LLVM_MAIN_SRC_DIR}/runtimes/libunwind/src/
     NO_DEFAULT_PATH
   )
 
   if (LIBCXXABI_LIBUNWIND_SOURCES STREQUAL "LIBCXXABI_LIBUNWIND_SOURCES-NOTFOUND")
     message(WARNING "LIBCXXABI_LIBUNWIND_SOURCES was not specified and couldn't be infered.")
     set(LIBCXXABI_LIBUNWIND_SOURCES "")
   endif()