support android ARGB format

[mgood7123]

No description provided.

[j-kaltes]

nanovg.h:
// Returns a color value from red, green, blue and alpha values.
NVGcolor nvgRGBA(unsigned char r, unsigned char g, unsigned char b, unsigned char a);

// Returns a color value from red, green, blue and alpha values.
NVGcolor nvgRGBAf(float r, float g, float b, float a);

See also: https://developer.android.com/reference/android/graphics/Color

constexpr const NVGcolor android2NVGcolor(const uint32_t get) {
        return {{{(((get>>16)&0xFF)/255.0f),(0xFF&(get>>8))/255.0f,(get&0xFF)/255.0f,(get>>24)/255.0f}}};
        }