Add check against null?

[QiAnXinCodeSafe]

Hi all,
There is a possible null pointer dereference issue found by Qihoo360 CodeSafe Team.
Details as bellow:

the return value of function FontPointer() may be a null pointer if there's an error.

daphne/daphne/daphne-1.0-src/video/SDL_DrawText.cpp

Lines 74 to 77 in 0258e2d

	/* Returns a pointer to the font struct of the number
	* returns NULL if theres an error
	*/
	static BitFont* FontPointer(int FontNumber)

after calling this function, there is no check for error nor check the return pointer against null.

daphne/daphne/daphne-1.0-src/video/SDL_DrawText.cpp

Lines 104 to 109 in 0258e2d

	BitFont *CurrentFont = FontPointer(FontType);
	/* see how many characters can fit on the screen */
	if(x>surface->w || y>surface->h) return;
	if(strlen(string) < (unsigned int) (surface->w-x)/CurrentFont->CharWidth)

Cheers
Qihoo360 CodeSafe Team