TableGen/GlobalISel: Fix using wrong type for instruction flags

09515f2 increased the size of the
MachineInstr flags from uint16_t to uint32_t, so change TableGen
to match.

Author: arsenm

llvm/utils/TableGen/Common/GlobalISel/GlobalISelMatchTable.h

@@ -55,7 +55,7 @@ enum {
   GISF_IgnoreCopies = 0x1,
 };
 
-using GISelFlags = std::uint16_t;
+using GISelFlags = std::uint32_t;
 
 //===- Helper functions ---------------------------------------------------===//