Simplify _readScreen2 for non-mobile builds #112

Job	Run time
Linux (GLideN64 (x64 Mupen64Plus-CLI))	3m 11s
Windows (GLideN64 (x64 Project64-Qt))	7m 14s
Linux (GLideN64 (x64 Mupen64Plus-Qt))	2m 44s
Windows (GLideN64 (x86 Project64-Qt))	7m 52s
Windows (GLideN64 (x64 Project64-WTL))	6m 36s
Windows (GLideN64 (x86 Project64-WTL))	5m 28s
Windows (GLideN64 (x64 Mupen64Plus-CLI))	5m 47s
Windows (GLideN64 (x86 Mupen64Plus-CLI))	5m 25s
Windows (GLideN64 (x64 Mupen64Plus-Qt))	8m 15s
Release	14s
	52m 46s

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