OpenSim crash fixes, thx to Henri and Zauber

indra/llrender/llfont.cpp

@@ -65,6 +65,8 @@ LLFontManager *gFontManagerp = NULL;
 
 FT_Library gFTLibrary = NULL;
 
+bool LLFont::sOpenGLcrashOnRestart = false;
+
 //static
 void LLFontManager::initClass()
 {
@@ -269,8 +271,11 @@ void LLFont::resetBitmapCache()
 	}
 	mFontBitmapCachep->reset();
 
+	if (!mIsFallback || !sOpenGLcrashOnRestart)	// because this often crashes under Linux...
+	{
 	// Add the empty glyph`5
 	addGlyph(0, 0);
+	}
 }
 
 LLFontGlyphInfo* LLFont::getGlyphInfo(const llwchar wch) const

indra/llrender/llfont.h

@@ -151,6 +151,8 @@ public:
 	F32 getXKerning(const llwchar char_left, const llwchar char_right) const; // Get the kerning between the two characters
 	virtual void reset() = 0;
 
+	static bool sOpenGLcrashOnRestart;
+
 protected:
 	virtual BOOL hasGlyph(const llwchar wch) const;		// Has a glyph for this character
 	virtual BOOL addChar(const llwchar wch) const;		// Add a new character to the font if necessary

indra/llrender/llfontgl.cpp

@@ -267,8 +267,16 @@ void LLFontGL::destroyAllGL()
 {
 	if (sFontRegistry)
 	{
+		if (LLFont::sOpenGLcrashOnRestart)
+		{
+			// This will leak memory but will prevent a crash...
+			sFontRegistry = NULL;
+		}
+		else
+		{
 		sFontRegistry->destroyGL();
 	}
+	}
 }
 
 void LLFontGL::destroyGL()