CMake: Don't export LLVM_INCLUDE_DIR to PARENT_SCOPE

The base change moved the LLVM rules out to a separate CMakeLists.txt file, while trying to keep the behaviour as close as possible to original. `LLVM_INCLUDE_DIR` is not needed to be exposed if we made it a public include directory on the llvm target, so do that.

Bug: b/145758253
Bug: b/152339534
Change-Id: I6e409da409d9a28847ac5bb4074899d70bb38145
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/42971
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Ben Clayton <bclayton@google.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index abb46e7..9a522d2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -593,7 +593,7 @@
 ###########################################################
 # LLVM
 ###########################################################
-add_subdirectory(third_party/llvm-7.0) # TODO(bclayton): This currently exports the LLVM_INCLUDE_DIR var. Don't.
+add_subdirectory(third_party/llvm-7.0)
 
 
 ###########################################################
@@ -771,7 +771,6 @@
 set(COMMON_INCLUDE_DIR
     ${SOURCE_DIR}
     ${CMAKE_CURRENT_SOURCE_DIR}/include
-    ${LLVM_INCLUDE_DIR}
     ${LIBBACKTRACE_INCLUDE_DIR}
 )
 set(OPENGL_INCLUDE_DIR
diff --git a/third_party/llvm-7.0/CMakeLists.txt b/third_party/llvm-7.0/CMakeLists.txt
index 0d4016d..89826c0 100644
--- a/third_party/llvm-7.0/CMakeLists.txt
+++ b/third_party/llvm-7.0/CMakeLists.txt
@@ -975,16 +975,9 @@
     COMPILE_DEFINITIONS "__STDC_CONSTANT_MACROS; __STDC_LIMIT_MACROS;"
     FOLDER "LLVM"
 )
+target_include_directories(llvm PUBLIC "${LLVM_INCLUDE_DIR}")
 
 # Add required libraries for LLVM
 if(LINUX)
     target_link_libraries(llvm dl)
 endif()
-
-
-###########################################################
-# Publics
-###########################################################
-# TODO(bclayton): Remove this and replace with:
-# target_include_directories(llvm PUBLIC "${LLVM_INCLUDE_DIR}")
-set(LLVM_INCLUDE_DIR ${LLVM_INCLUDE_DIR} PARENT_SCOPE)