r300g: fix sRGB->sRGB blits
r300g: fix sRGB->sRGB blits

Cc: 10.5 10.4 <59f39c0db42d4479a46b02d4d2bc11120e37bb44@lists.freedesktop.org>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler