enclose FreeType in a C++ namespace
Migrated from: [SAVANNAH-45676]
Werner LEMBERG reported:
Graham Asher suggests the following to put all FreeType functions into a separate namespace.
(i) allow the meaning of FT_BEGIN_HEADER to be either nothing, or 'extern "C"' or 'namespace {' as a configuration option.
(ii) enclose the meat (after #includes) of all source files in FT_BEGIN_SOURCE ... FT_END_SOURCE, and allow FT_BEGIN_SOURCE to be either nothing or 'namespace {', etc.