Add support for Unicode strings in CMICmnLLDBUtilSBValue::GetValue (MI)

This patch includes the following changes:
# Add CMIUtilString::ConvertToASCII to convert unicode to ASCII (MI)
# Rework CMICmnLLDBUtilSBValue::GetSimpleValue to print wide/unicode char (MI)
## Add CMICmnLLDBUtilSBValue::GetSimpleValueChar
## Extend CMICmnLLDBUtilSBValue::IsCharType to accept char16_t/char32_t
## Don't ignore the fail_value in SBValue::GetValueAsUnsigned
# Rework CMIUtilString::ConvertToASCII (MI)
## Don't use templates
## Change the function signature to convert signle characters (was std::basic_string)
## Rename CMIUtilString::ConvertToASCII to CMIUtilString::ConvertToPrintableASCII
# Add CMIUtilString::ConvertToPrintableASCII for char (MI)
## Refactor CMIUtilString::Escape
## Simplify CMICmnLLDBUtilSBValue::GetSimpleValueChar for char
# Add char16_t* and char32_t* support in CMICmnLLDBUtilSBValue::GetSimpleValue (MI)
## Add CMICmnLLDBUtilSBValue::GetSimpleValueCStringPointer
## Add CMICmnLLDBUtilSBValue::ReadCStringFromHostMemory2
   (it's extended version of CMICmnLLDBUtilSBValue::ReadCStringFromHostMemory)
# Improve error checking in CMICmnLLDBUtilSBValue::GetSimpleValueChar (MI)
# Refactor CMICmnLLDBUtilSBValue (MI)
## Remove CMICmnLLDBUtilSBValue::ReadCStringFromHostMemory
   (use CMICmnLLDBUtilSBValue::ReadCStringFromHostMemory2 instead)
## Rename CMICmnLLDBUtilSBValue::ReadCStringFromHostMemory2 to
   CMICmnLLDBUtilSBValue::ReadCStringFromHostMemory
## Move CMICmnLLDBUtilSBValue::GetValueCString to private methods
## Rename CMICmnLLDBUtilSBValue::GetValueCString to
   CMICmnLLDBUtilSBValue::GetSimpleValueCStringArray
## Remove CMICmnLLDBUtilSBValue::GetChildValueCString
# Improve MiGdbSetShowTestCase.test_lldbmi_gdb_set_show_print_char_array_as_string test to check char16_t/char32_t (MI)
# Fix CMICmnLLDBUtilSBValue::GetSimpleValueCStringArray for Unicode (MI)
## Fix handling of char16_t and char32_t
## Improve CMICmnLLDBUtilSBValue::ReadCStringFromHostMemory to read
   variables of type char[]: add vnMaxLen argument
## Turn on few cases to check char16_t[] and char32_t[] output in
   MiGdbSetShowTestCase.test_lldbmi_gdb_set_show_print_char_array_as_string
# Remove unnecessary checks in CMICmnLLDBUtilSBValue (MI)

llvm-svn: 236827