update_cpu_features: rename generic arc model to arcv2

lib/std/Target.zig

@@ -2048,6 +2048,7 @@ pub const Cpu = struct {
                 .aarch64, .aarch64_be => &aarch64.cpu.armv8a,
                 .alpha => &alpha.cpu.ev4,
                 .amdgcn => &amdgcn.cpu.gfx600,
+                .arc, .arceb => &arc.cpu.arcv2,
                 .avr => &avr.cpu.avr1,
                 .bpfel, .bpfeb => &bpf.cpu.v1,
                 .csky => &csky.cpu.e2,

lib/std/Target/arc.zig

@@ -31,8 +31,8 @@ pub const all_features = blk: {
 };
 
 pub const cpu = struct {
-    pub const generic: CpuModel = .{
-        .name = "generic",
+    pub const arcv2: CpuModel = .{
+        .name = "arcv2",
         .llvm_name = "generic",
         .features = featureSet(&[_]Feature{}),
     };

tools/update_cpu_features.zig

@@ -1206,6 +1206,12 @@ const targets = [_]ArchTarget{
             .name = "ARC",
             .td_name = "ARC",
         },
+        .model_overrides = &.{
+            .{
+                .llvm_name = "generic",
+                .zig_name = "arcv2",
+            },
+        },
     },
     .{
         .zig_name = "arm",