util: rework _MSC_VER >= 1200 checks
util: rework _MSC_VER >= 1200 checks

Replace the _MSC_VER >= 1200 with defined (_MSC_VER) and compact if/else
statements. We require MSVC 2008 or later with commit 46110c5d564.

Signed-off-by: Emil Velikov <4c996f2f093ddd0585a556460b4cc3ba555546ef@gmail.com>
Reviewed-by: Brian Paul <3cb4e1df5ec4da2c7c4af7c52cec8cf340a55a10@vmware.com>
Reviewed-by: Jose Fonseca <61b5a29db2c0650f7c8510f93eece059c1b09320@vmware.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler