[rtext] isGpuReady flag in ExportFontAsCode

[hatkidchan]

Please, before submitting a new issue verify and check:

• I tested it on latest raylib version from master branch
• I checked there is no similar issue already reported
• I checked the documentation on the wiki
• My code has no errors or misuse of raylib

Issue description

Since 4c9282b, ExportFontAsCode function also uses isGpuReady flag, which is not available publicly.
When using exported font (by #includeing it and calling LoadFont_XXX()), you can't even compile the file that's using the #included font.

As a workaround you can add const bool isGpuReady = true; before the #include.

Environment

N/A

Issue Screenshot

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Code Example

#include <stdlib.h>
#include <raylib.h>

int main(void) {
  InitWindow(0, 0, "");
  Font font = LoadFontEx("font.ttf", 16, 0, 256);
  ExportFontAsCode(font, "font.h");
  UnloadFont(font);
}

And observe font.h

[raysan5]

@hatkidchan Good catch! Actually that function shouldn't be checking if isGpuReady... That mechanism was a bad idea, I need to review it in some other way.