Remove libunwind disabled warnings. (dotnet#67042)

src/native/external/libunwind/CMakeLists.txt

@@ -54,9 +54,6 @@ if ("${CMAKE_GENERATOR}" MATCHES "^Visual Studio.*$")
 
   # Warnings in release builds
   add_compile_options(-wd4068) # ignore unknown pragma warnings (gcc pragmas)
-  add_compile_options(-wd4146) # minus operator applied to unsigned
-  add_compile_options(-wd4244) # possible loss of data
-  add_compile_options(-wd4267) # possible loss of data
   add_compile_options(-wd4334) # 32-bit shift implicitly converted to 64 bits
 
   # Disable warning due to incorrect format specifier in debugging printf via the Debug macro
@@ -87,7 +84,7 @@ if ("${CMAKE_GENERATOR}" MATCHES "^Visual Studio.*$")
   if (NOT HAVE_STDATOMIC_H)
     configure_file(include/win/fakestdatomic.h.in ${CMAKE_CURRENT_BINARY_DIR}/include/stdatomic.h)
   endif (NOT HAVE_STDATOMIC_H)
-  
+
   # MSVC compiler is currently missing C11 _Thread_local
   check_c_source_compiles("void main() { _Thread_local int a; }"  HAVE_THREAD_LOCAL)
   if (NOT HAVE_THREAD_LOCAL)