Use LLVM new pass manager for wamrc (#978)

Use LLVM new pass manager for wamrc to replace the legacy pass manger,
so as to gain better performance and reduce the compilation time.
Reference links:
- https://llvm.org/docs/NewPassManager.html
- https://blog.llvm.org/posts/2021-03-26-the-new-pass-manager

And add an option to use the legacy pm mode when building wamrc:
cmake .. -DWAMR_BUILD_LLVM_LEGACY_PM=1

For JIT mode, keep it unchanged as it only runs several function passes and
using new pass manager will increase the compilation time.

And refactor the codes of applying LLVM passes.

wamr-compiler/CMakeLists.txt

@@ -36,6 +36,10 @@ add_definitions(-DWASM_ENABLE_CUSTOM_NAME_SECTION=1)
 add_definitions(-DWASM_ENABLE_DUMP_CALL_STACK=1)
 add_definitions(-DWASM_ENABLE_PERF_PROFILING=1)
 
+if (WAMR_BUILD_LLVM_LEGACY_PM EQUAL 1)
+  add_definitions(-DWASM_ENABLE_LLVM_LEGACY_PM=1)
+endif()
+
 # Set WAMR_BUILD_TARGET, currently values supported:
 # "X86_64", "AMD_64", "X86_32", "ARM_32", "MIPS_32", "XTENSA_32"
 if (NOT WAMR_BUILD_TARGET)