LLVM_REQUIRES_* variables shound't be set (#4850)

The `LLVM_REQUIRES_*` variables are internal variables in LLVM's
configuration used to determine if a build setting is required, they
don't actually control the build setting itself, so we shouldn't be
setting them.

`LLVM_ENABLE_*` variables control the build settings, and we do set
those correctly.

cmake/caches/PredefinedParams.cmake

@@ -29,8 +29,6 @@ set(LLVM_ENABLE_RTTI ON CACHE BOOL "")
 set(LLVM_INCLUDE_DOCS OFF CACHE BOOL "") 
 set(LLVM_INCLUDE_EXAMPLES OFF CACHE BOOL "") 
 set(LLVM_OPTIMIZED_TABLEGEN OFF CACHE BOOL "") 
-set(LLVM_REQUIRES_EH ON CACHE BOOL "") 
-set(LLVM_REQUIRES_RTTI ON CACHE BOOL "") 
 set(LLVM_TARGETS_TO_BUILD "None" CACHE STRING "")
 set(LIBCLANG_BUILD_STATIC ON CACHE BOOL "") 
 set(CLANG_BUILD_EXAMPLES OFF CACHE BOOL "") 

utils/hct/hctbuild.cmd

@@ -308,7 +308,6 @@ set CMAKE_OPTS=%CMAKE_OPTS% -DLLVM_INCLUDE_DOCS:BOOL=OFF -DLLVM_INCLUDE_EXAMPLES
 set CMAKE_OPTS=%CMAKE_OPTS% -DLIBCLANG_BUILD_STATIC:BOOL=ON
 rem set CMAKE_OPTS=%CMAKE_OPTS% -DLLVM_OPTIMIZED_TABLEGEN:BOOL=ON
 set CMAKE_OPTS=%CMAKE_OPTS% -DLLVM_OPTIMIZED_TABLEGEN:BOOL=OFF
-set CMAKE_OPTS=%CMAKE_OPTS% -DLLVM_REQUIRES_EH:BOOL=ON
 set CMAKE_OPTS=%CMAKE_OPTS% -DLLVM_APPEND_VC_REV:BOOL=ON
 
 rem Enable exception handling (which requires RTTI).
@@ -319,7 +318,6 @@ rem Setup a specific, stable triple for HLSL.
 set CMAKE_OPTS=%CMAKE_OPTS% -DLLVM_DEFAULT_TARGET_TRIPLE:STRING=dxil-ms-dx
 
 set CMAKE_OPTS=%CMAKE_OPTS% -DCLANG_BUILD_EXAMPLES:BOOL=OFF
-set CMAKE_OPTS=%CMAKE_OPTS% -DLLVM_REQUIRES_RTTI:BOOL=ON
 set CMAKE_OPTS=%CMAKE_OPTS% -DCLANG_CL:BOOL=OFF
 set CMAKE_OPTS=%CMAKE_OPTS% -DCMAKE_SYSTEM_VERSION=%DXC_CMAKE_SYSTEM_VERSION%