mesa: Replace deprecated __MSC__ macro.

src/mesa/main/imports.h

@@ -333,7 +333,7 @@ static INLINE int iround(float f)
    return r;
 }
 #define IROUND(x)  iround(x)
-#elif defined(USE_X86_ASM) && defined(__MSC__) && defined(__WIN32__)
+#elif defined(USE_X86_ASM) && defined(_MSC_VER)
 static INLINE int iround(float f)
 {
    int r;

src/mesa/math/m_debug_util.h

@@ -303,7 +303,7 @@ enum { NIL = 0, ONE = 1, NEG = -1, VAR = 2 };
  */
 #if defined(__GNUC__)
 #  define ALIGN16(type, array)	type array __attribute__ ((aligned (16)))
-#elif defined(__MSC__)
+#elif defined(_MSC_VER)
 #  define ALIGN16(type, array)	type array __declspec(align(16)) /* GH: Does this work? */
 #elif defined(__WATCOMC__)
 #  define ALIGN16(type, array)	                    /* Watcom does not support this */