Mute some compiler warnings in the generated python wrapper code.

[teemperor]

Summary

With SWIG 3.0.12 I get the following compiler warnings when compiling LLDB:

tools/lldb/scripts/LLDBWrapPython.cpp:23699:52: warning: format string is not a string literal (potentially insecure) [-Wformat-security]
    result = (int)(arg1)->SetErrorStringWithFormat((char const *)arg2);
                                                   ^             ~~~~
tools/lldb/scripts/LLDBWrapPython.cpp:23699:52: note: treat the string as an argument to avoid this
    result = (int)(arg1)->SetErrorStringWithFormat((char const *)arg2);
                                                   ^
                                                   "%s", 
tools/lldb/scripts/LLDBWrapPython.cpp:52418:21: warning: comparison of integers of different signs: 'int' and 'uint32_t' (aka 'unsigned int') [-Wsign-compare]
      for (i = 0; i < arg3; i++) {
                  ~ ^ ~~~~
tools/lldb/scripts/LLDBWrapPython.cpp:52510:21: warning: comparison of integers of different signs: 'int' and 'uint32_t' (aka 'unsigned int') [-Wsign-compare]
      for (i = 0; i < arg3; i++) {
                  ~ ^ ~~~~
tools/lldb/scripts/LLDBWrapPython.cpp:52611:21: warning: comparison of integers of different signs: 'int' and 'uint32_t' (aka 'unsigned int') [-Wsign-compare]
      for (i = 0; i < arg3; i++) {
                  ~ ^ ~~~~

As the code is anyway generated we probably should disable those two warnings for the source file.

[teemperor]

It seems people are also in favor of completely disabling the warnings, so that patch will replace this one.

source/API/CMakeLists.txt

 
 if (LLVM_ENABLE_WERROR)
   if (MSVC)
     set_property(SOURCE ${LLDB_WRAP_PYTHON} APPEND_STRING PROPERTY COMPILE_FLAGS " /W0")
   else()
     set_property(SOURCE ${LLDB_WRAP_PYTHON} APPEND_STRING PROPERTY COMPILE_FLAGS " -w")
   endif()
 endif()
+
+if (NOT MSVC)
+  # The generated code triggers some compiler warnings that we can ignore.
+  set_property(SOURCE ${LLDB_WRAP_PYTHON} APPEND_STRING PROPERTY COMPILE_FLAGS " -Wno-sign-compare -Wno-format-security")
+endif()
+
 set_source_files_properties(${LLDB_WRAP_PYTHON} PROPERTIES GENERATED 1)
 if (CLANG_CL)
   set_property(SOURCE ${LLDB_WRAP_PYTHON} APPEND_STRING
     PROPERTY COMPILE_FLAGS " -Wno-unused-function")
 endif()
 if (LLVM_COMPILER_IS_GCC_COMPATIBLE AND
     NOT "${CMAKE_SYSTEM_NAME}" MATCHES "Darwin")
   set_property(SOURCE ${LLDB_WRAP_PYTHON} APPEND_STRING