Correct WinAdapter path assumptions in public headers (#5003)

dxcapi.h and dxcisense.h had inconsistent and unhelpful for release
include paths to find WinAdapter.h. By adding the necessary -I flag,
the include can be found without including the paths

Fixes #4918

(cherry picked from commit 00da3ab)

Author: Greg Roth

CMakeLists.txt

@@ -608,6 +608,7 @@ endif()
 
 include_directories( ${LLVM_INCLUDE_DIR} ${LLVM_MAIN_INCLUDE_DIR})
 
+include_directories( ${LLVM_MAIN_INCLUDE_DIR}/dxc/Support) # HLSL Change
 include_directories( ${LLVM_INCLUDE_DIR}/dxc/Tracing) # HLSL Change
 
 # when crosscompiling import the executable targets from a file

include/dxc/dxcapi.h

@@ -34,7 +34,7 @@
 #else
 
 #include <dlfcn.h>
-#include "dxc/Support/WinAdapter.h"
+#include "WinAdapter.h"
 #endif
 
 struct IMalloc;

include/dxc/dxcisense.h

@@ -14,7 +14,7 @@
 
 #include "dxcapi.h"
 #ifndef _WIN32
-#include "Support/WinAdapter.h"
+#include "WinAdapter.h"
 #endif
 
 typedef enum DxcGlobalOptions