[misc] Remove some unnecessary #include lines (#4265)

Author: PGZXB

taichi/backends/cc/codegen_cc.cpp

@@ -7,9 +7,6 @@
 #include "taichi/ir/transforms.h"
 #include "taichi/util/line_appender.h"
 #include "taichi/util/str.h"
-#ifdef TI_WITH_LLVM
-#include "taichi/llvm/llvm_program.h"
-#endif
 #include "cc_utils.h"
 
 #define C90_COMPAT 0

taichi/backends/wasm/aot_module_builder_impl.h

@@ -5,6 +5,7 @@
 
 #include "taichi/program/aot_module.h"
 #include "taichi/program/kernel.h"
+#include "taichi/llvm/llvm_fwd.h"
 
 #include "taichi/backends/wasm/codegen_wasm.h"
 

taichi/jit/jit_module.h

@@ -4,7 +4,6 @@
 #include <functional>
 
 #include "taichi/inc/constants.h"
-#include "taichi/llvm/llvm_fwd.h"
 #include "taichi/lang_util.h"
 #include "taichi/program/kernel_profiler.h"
 

taichi/system/snode_tree_buffer_manager.h

@@ -1,5 +1,4 @@
 #pragma once
-#include "taichi/llvm/llvm_context.h"
 #include "taichi/inc/constants.h"
 #include "taichi/struct/snode_tree.h"
 #define TI_RUNTIME_HOST
@@ -10,6 +9,7 @@ using Ptr = uint8_t *;
 
 TLANG_NAMESPACE_BEGIN
 
+class JITModule;
 class ProgramImpl;
 
 class SNodeTreeBufferManager {