spirv: cannot build libc

SPIR-V cannot build libc, ssp, compiler-rt, etc at the time of this commit, so
prevent trying to build them.

lib/std/target.zig

@@ -944,7 +944,7 @@ pub const Target = struct {
                 };
             }
 
-            pub fn isSPIRV(arch: Arch) bool {
+            pub fn isSpirV(arch: Arch) bool {
                 return switch (arch) {
                     .spirv32, .spirv64 => true,
                     else => false,
@@ -1534,6 +1534,10 @@ pub const Target = struct {
         return !self.cpu.arch.isWasm();
     }
 
+    pub fn isSpirV(self: Target) bool {
+        return self.cpu.arch.isSpirV();
+    }
+
     pub const FloatAbi = enum {
         hard,
         soft,

src/Compilation.zig

@@ -722,10 +722,11 @@ pub fn create(gpa: Allocator, options: InitOptions) !*Compilation {
     // Once they are capable this condition could be removed. When removing this condition,
     // also test the use case of `build-obj -fcompiler-rt` with the native backends
     // and make sure the compiler-rt symbols are emitted.
-    const capable_of_building_compiler_rt = build_options.have_llvm and options.target.os.tag != .plan9;
-
-    const capable_of_building_zig_libc = build_options.have_llvm and options.target.os.tag != .plan9;
-    const capable_of_building_ssp = build_options.have_llvm and options.target.os.tag != .plan9;
+    const is_p9 = options.target.os.tag == .plan9;
+    const is_spv = options.target.cpu.arch.isSpirV();
+    const capable_of_building_compiler_rt = build_options.have_llvm and !is_p9 and !is_spv;
+    const capable_of_building_zig_libc = build_options.have_llvm and !is_p9 and !is_spv;
+    const capable_of_building_ssp = build_options.have_llvm and !is_p9 and !is_spv;
 
     const comp: *Compilation = comp: {
         // For allocations that have the same lifetime as Compilation. This arena is used only during this

src/target.zig

@@ -163,7 +163,7 @@ pub fn canBuildLibC(target: std.Target) bool {
 pub fn cannotDynamicLink(target: std.Target) bool {
     return switch (target.os.tag) {
         .freestanding, .other => true,
-        else => false,
+        else => target.isSpirV(),
     };
 }
 
@@ -331,18 +331,18 @@ pub fn supportsStackProbing(target: std.Target) bool {
 }
 
 pub fn supportsStackProtector(target: std.Target) bool {
-    _ = target;
-    return true;
+    return !target.isSpirV();
 }
 
 pub fn libcProvidesStackProtector(target: std.Target) bool {
-    return !target.isMinGW() and target.os.tag != .wasi;
+    return !target.isMinGW() and target.os.tag != .wasi and !target.isSpirV();
 }
 
 pub fn supportsReturnAddress(target: std.Target) bool {
     return switch (target.cpu.arch) {
         .wasm32, .wasm64 => target.os.tag == .emscripten,
         .bpfel, .bpfeb => false,
+        .spirv32, .spirv64 => false,
         else => true,
     };
 }