build: add spirv to dev env

src/dev.zig

@@ -40,6 +40,10 @@ pub const Env = enum {
     /// - `zig build-* -fno-llvm -fno-lld -target riscv64-linux`
     @"riscv64-linux",
 
+    /// - sema
+    /// - `zig build-* -fno-llvm -fno-lld -target spirv(32/64)-* --listen=-`
+    spirv,
+
     /// - sema
     /// - `zig build-* -fno-llvm -fno-lld -target wasm32-* --listen=-`
     wasm,
@@ -178,6 +182,12 @@ pub const Env = enum {
                 => true,
                 else => Env.sema.supports(feature),
             },
+            .spirv => switch (feature) {
+                .spirv64_backend,
+                .spirv_linker,
+                => true,
+                else => Env.sema.supports(feature),
+            },
             .wasm => switch (feature) {
                 .stdio_listen,
                 .incremental,