mesa: fix format conversion bug in get_tex_rgba_uncompressed()
mesa: fix format conversion bug in get_tex_rgba_uncompressed()

We need to set the need_convert flag with each loop iteration, not
just when the rgba pointer is null.

Bug reported by Markus Müller <mueller@imfusion.de> on mesa-users list.
Fixes new piglit arb_texture_float-get-tex3d test.

Cc: <59f39c0db42d4479a46b02d4d2bc11120e37bb44@lists.freedesktop.org>
Reviewed-by: Anuj Phogat <e2026475996c48f0b97fd37e84129b3912980428@gmail.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler