fix for SH-1498: crash at LLImageGL::deleteDeadTextures() line 1429
fix for SH-1498: crash at LLImageGL::deleteDeadTextures() line 1429

gabeharms/firestorm,gabeharms/firestorm,gabeharms/firestorm,gabeharms/firestorm,gabeharms/firestorm,gabeharms/firestorm,gabeharms/firestorm,gabeharms/firestorm,gabeharms/firestorm