* Update Froxelizer.h
Fix this error when building with msvc from vs2019
error C2926: 'filament::details::Froxelizer::FroxelEntry::<unnamed-tag>::offset': a default member initializer is not allowed for a member of an anonymous struct within a union
* Fix some compilation issues with vs2019/msvc
Program.cpp:
1>C:\greg\github\filament\filament\backend\src\Program.cpp(28,42): error C2610: 'filament::backend::Program::Program(void) noexcept': is not a special member function or comparison operator which can be defaulted
1>C:\greg\github\filament\filament\backend\src\Program.cpp(28,42): message : exception specification does not match the implicitly declared specification.
GLUtils.h: __PRETTY_FUNCTION__ macro is clang specific. Use MSVC equivalent
Color.h: fix warning
* #1493 - inline constructor in definition as requested by @romainguy
* #1493 "move this #define inside the #else below" as requested
* #1493 revert last change which causes compilation failures on other platforms.
provide empty implementation of Program::Program() in Program.cpp
* More fixes for building with vs2019/msvc
* #1500 use consistent macro definition syntax (@bejado)
* #1500 simplify DEBUG_COMMAND macro as requested by @pixelflinger
* #1500 use `{ 0 }` which is accepted by Visual Studio (` = 0 ` is not accepted)
* #1500 remove incorrect UTILS_RESTRICT alltogether
